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Chemistry M.C.Q (1 Marks)

The p-Block Elements · Gujarat Board (GSEB) STD 11 Science (GSEB - English Medium). 164 questions.

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M.C.Q (1 Marks)

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164 questions · auto-graded multiple-choice test.

MCQ 11 Mark
In the structure of diborane.
  • A
    All hydrogen atoms lie in one plane and boron atoms lie in a plane perpendicular to this plane.
  • ✓
    $2$ boron atoms and $4$ terminal hydrogen atoms lie in the same plane and $2$ bridging hydrogen atoms lie in the perpendicular plane.
  • C
    $4$ bridging hydrogen atoms and boron atoms lie in one plane and two terminal hydrogen atoms lie in a plane perpendicular to this plane.
  • D
    All the atoms are in the same plane.
Answer
Correct option: B.
$2$ boron atoms and $4$ terminal hydrogen atoms lie in the same plane and $2$ bridging hydrogen atoms lie in the perpendicular plane.
The four terminal hydrogen atoms and the two boron atoms lie in one plane.
Above and below this plane, there are two bridging hydrogen atoms. The four terminal $\ce{B-H}$ bonds are regular two$-$center$-$two$-$electron bonds while the two bridge $\text{(B-H-B)}$ bonds are different and can be described in terms of three$-$centre$-$two$-$electrone bonds as shown in figure:
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MCQ 21 Mark
$\ce{B_2H_6}$ on heating with $\ce{NH_3}$ gases gives:
  • ✓
    $ \mathrm{B}_3 \mathrm{~N}_3 \mathrm{H}_6$
  • B
    $ \mathrm{~B}_2 \mathrm{H}_6 \cdot \mathrm{NH}_3 $
  • C
    $\mathrm{H}_6 \cdot 3 \mathrm{NH}_3 $
  • D
    $\mathrm{~B}_2 \mathrm{~N}_4 \mathrm{H}_{10} $
Answer
Correct option: A.
$ \mathrm{B}_3 \mathrm{~N}_3 \mathrm{H}_6$
$3\text{B}_2\text{H}_6+6\text{NH}_3\rightarrow2\text{B}_3\text{N}_3\text{H}_6+12\text{H}_2\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{(Inorganic benzene)}$
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MCQ 31 Mark
Catenation i.e., linking of similar atoms depends on size and electronic configuration of atoms. The tendency of catenation in Group $14$ elements follows the order:
  • A
    $\text{C > Si > Ge > Sn.}$
  • ✓
    $\text{C >> Si > Ge ≈ Sn.}$
  • C
    $\text{Si > C > Sn > Ge.}$
  • D
    $\text{Ge > Sn > Si > C.}$
Answer
Correct option: B.
$\text{C >> Si > Ge ≈ Sn.}$
The decrease in catenation property is linked with $M – M$ bond energy which decreases from carbon to tin.
$\text{C}-\text{C}\ \ \ \ \ \ \ \ \text{Si}-\text{S}\ \ \ \ \ \ \ \ \text{Ge}-\text{Ge}\ \ \ \ \ \ \ \ \text{Sn}-\text{Sn}\\^{83\text{kcal/ mol}}\ \ \ \ ^{54\text{kcal/ mol}}\ \ \ \ ^{40\text{kcal/ mol}}\ \ \ \ \ \ \ \ ^{37\text{kcal/ mol}}$
Thus, two options $(a)$ and $(b)$ are correct in this question but $(b)$ is more approprite.
$\text{C}>>\text{Si}\ \ \ \ \ \ > \ \ \ \ \ \text{Ge}\approx\text{Sn}\\ ^{\text{large difference}\\ \ \ \ \text{in energy}}\ \ \ \ \ \ \ \ \ \ ^{\text{Small difference}\\ \ \ \ \text{in energy}}$
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MCQ 41 Mark
Kieselguhr contains :
  • A
    Carbon
  • ✓
    Silicon
  • C
    Boron
  • D
    Iodine
Answer
Correct option: B.
Silicon
Keisulguhr is a naturally occurring soft silicons sedimentary rock that is easily crumbled into fine white$-$to$-$off$-$white powder. It contains $80−90\%$ silica, with $2−4\%$ alumina. So it has silicon.
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MCQ 51 Mark
Which of the following figures show$(s)$ the bonding in diborane?
  • A
  • B
  • ✓
    Both $(A)$ and $(b)$
  • D
    None of these.
Answer
Correct option: C.
Both $(A)$ and $(b)$
In the structure of diborane, each $B$ atom uses $sp^3$-hybridised orbital for bonding. Out of the four $sp^3 -$hybridised orbitals on each $B$ atom, one is without an electron shown by dotted lines. The terminal $B-H$ bonds are normal $2$ centre$-2$ electron bonds but the two bridge bonds are $3$ centre$-2$ electron bonds. The $3$ centre$-2$ electron bridge bonds are also refered as banana bonds.
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MCQ 61 Mark
In representative elements the ionization energy values generally decrease smoothly down the group. But in boron group the values show an erratic trend. This is mainly due to:
  • A
    increase in metallic nature down the group
  • B
    inert pair effect in the heavier elements of the group
  • ✓
    $d-$block contraction and lanthanide contraction affecting the values of later elements due to poor shielding by $d$ and $f$ electrons
  • D
    The different type of packing in their crystalline structure
Answer
Correct option: C.
$d-$block contraction and lanthanide contraction affecting the values of later elements due to poor shielding by $d$ and $f$ electrons
Poor shielding of nuclear charge in $Ga$ by $3d$ electrons results in smaller atomic size and higher $I.P$ for the atom. Similarly, in $TI$ the poor shielding by the $4f$ electrons leads to higher $I.P$ or the atom. Hence, first $I.P$ values for the $3^{rd}$ group elements show erratic trend.
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MCQ 71 Mark
Which of the following statements about anhydrous aluminium chloride is correct?
  • ✓
    It exists as $\ce{AlCl_3}$​ molecule in vapour.
  • B
    It is a strong Lewis base.
  • C
    It sublimes at $100^{\circ}C$ under vacuum.
  • D
    It is not readily hydrolyzed
Answer
Correct option: A.
It exists as $\ce{AlCl_3}$​ molecule in vapour.
It exists as dimer in vapour.
It is a strong Lewis acid due to incomplete octet and because of that it can be easily hydrolyzed.
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MCQ 81 Mark
The coloured bead produced when borax is heated with $Cu$ in an oxidizing flame is:
  • A
    Greenish
  • ✓
    Green when hot $\&$ blue when cold
  • C
    Yellow
  • D
    Red
Answer
Correct option: B.
Green when hot $\&$ blue when cold
The coloured metaborate $\mathrm{Cu}\left(\mathrm{BO}_2\right)_2$​ formed when borax is heated with $Cu$ is green when hot and blue when cold.
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MCQ 91 Mark
The element which exists in liquid state for a wide range of temperature and can be used for measuring high temperature is :
  • A
    $B.$
  • B
    $Al.$
  • ✓
    $Ga.$
  • D
    $In.$
Answer
Correct option: C.
$Ga.$
The melting point of gallium is $30^{\circ} C$ and boiling point is $2240^{\circ} C$. Thus, the element exists in liquid state for a wide range of temperature.
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MCQ 101 Mark
Boric acid is an acid because its molecule.
  • A
    Contains replaceable $H^+$ ion.
  • B
    Gives up a proton.
  • ✓
    Accepts $OH^-$ from water releasing proton.
  • D
    Combines with proton from water molecule.
Answer
Correct option: C.
Accepts $OH^-$ from water releasing proton.
Because of the small size of boron atom and presence of only six electrons in its valence shell, $\ce{B(OH)_3}$ accepts a pair of electrons from $\ce{OH^-}$ ion of $\ce{H_2O}$, releasing a proton.
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MCQ 111 Mark
Which of the following has trigonal planar geometry?
  • ✓
    $\ce{BF_3}$
  • B
    $\ce{NH_3}$
  • C
    $\ce{PCI_3}$
  • D
    $\ce{IF_3}$
Answer
Correct option: A.
$\ce{BF_3}$
$\ce{BF_3 , p^2}$ hybridised, trigonal planar, bond angle $120^{\circ}$
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MCQ 121 Mark
Element showing the phenomenon of allotropy is:
  • ✓
    $Al$
  • B
    $Pb$
  • C
    $Sn$
  • D
    $Cu$
Answer
Correct option: A.
$Al$
Among the given elements tin $(Sn)$ shows the allotropy.
$\beta$-$tin ($the metallic form, or white tin$)$, which is stable at and above room temperature, is malleable. In contrast, $\alpha - tin ($nonmetallic form, or gray tin$)$, which is stable below $13.2^{\circ}C (55.8^{\circ}F),$ is brittle.
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MCQ 131 Mark
Which of the following is not isostructural with $\ce{SicI_4}$?
  • A
    $\text{SO}^{2-}_4$
  • B
    $\text{PO}^{3-}_4$
  • C
    $\text{NH}^{+}_4$
  • ✓
    $\text{Scl}_4$
Answer
Correct option: D.
$\text{Scl}_4$
$\ce{Scl_4}$ is not isostructural, it has sea$-$saw shope, others are tetrahedral.
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MCQ 141 Mark
Which of the following is a Lewis acid?
  • ✓
    $\ce{AlCl_3}$.
  • B
    $\ce{MgCl_2}$.
  • C
    $\ce{CaCl_2}$.
  • D
    $\ce{BaCl_2}$.
Answer
Correct option: A.
$\ce{AlCl_3}$.
Lewis acids are the species in which octate is not complete and ready to accept electrons. In $\ce{AlCl_3},Al$ is surrounded by $6$ electrons and all three $Cl$ atoms are surrounded by $8$ electrons, therefore, $\ce{AlCl_3}$ is electron accepter. It is a covalent compound.
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MCQ 151 Mark
Indite is a mineral for the production of $.........$
  • ✓
    indium
  • B
    aluminium
  • C
    boron
  • D
    gallium
Answer
Correct option: A.
indium
Indite is an extremely rare indium$-$iron sulfide mineral, found in Siberia.
Its chemical formula is $\ce{FeIn_2​S_4}$.
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MCQ 161 Mark
Borax is :
  • A
    Miscible in water.
  • B
    Immiscible in oil.
  • ✓
    Partially soluble in cold water $\&$ fairly soluble in hot water.
  • D
    Insoluble in water.
Answer
Correct option: C.
Partially soluble in cold water $\&$ fairly soluble in hot water.
Borax slightly soluble in cold water, very soluble in hot water and insoluble in acids.
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MCQ 171 Mark
How many electrons can fit in the orbital for which n = 3 and l = 1?
  • A
    10
  • B
    14
  • C
    2
  • ✓
    6
Answer
Correct option: D.
6
Explanation: d. 6
n = 3 and l = 1
⇒ 3p orbital so 3p orbital can accommodate 6 electrons.
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MCQ 181 Mark
Total number of sigma bonds formed by all the boron atoms in borax is:
  • ✓
    $14$
  • B
    $4$
  • C
    $9$
  • D
    $7$
Answer
Correct option: A.
$14$
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MCQ 191 Mark
Which of the following is a white crystalline solid, with soapy touch?
  • A
    Borax.
  • ✓
    Orthoboric acid.
  • C
    Diborane.
  • D
    None of these.
Answer
Correct option: B.
Orthoboric acid.
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MCQ 201 Mark
Vapour pressure of a solvent containing nonvolatile solute is $.........$
  • A
    more than the vapour pressure of a solvent
  • ✓
    less than the vapour pressure of solvent
  • C
    equal to the vapour pressure of solvent
  • D
    none
Answer
Correct option: B.
less than the vapour pressure of solvent
At any given temperature, the vapor pressure of a solution containing a nonvolatile solute is less than that of the pure solvent. This effect is called vapor pressure lowering. The solid line in Figure is a plot of the vapor pressure of pure water versus temperature. The break in the curve at $0^{\circ} C$ is the intersection of the curve of the vapor pressure of the solid with the curve of the vapor pressure of the liquid. The dashed line in is a plot of the vapor pressure of an aqueous solution of sugar versus temperature. Notice that the vapor pressure of the solution is always less than that of the pure solvent.
The vapor pressure of pure water is shown as a solid line; the vapor pressure of an aqueous solution is shown as a dashed line. Note the differences between the solution and the pure substance in melting point and boiling point.
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MCQ 211 Mark
Cement, the important building material is a mixture of oxides of several elements. Besides calcium, iron and sulphur, oxides of elements of which of the group $(s)$ are present in the mixture?
  • A
    Group $2$
  • ✓
    Groups $2, 13$ and $14$
  • C
    Groups $2$ and $13$
  • D
    Groups $2$ and $14$
Answer
Correct option: B.
Groups $2, 13$ and $14$
groups $2(\mathrm{MgO})$, Group $13\left(\mathrm{Al}_2 \mathrm{O}_3\right)$, Group $14\left(\mathrm{SiO}_2\right)$.
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MCQ 221 Mark
Borax contains the tetranuclear units. Thus, its formula can be written as:
  • A
    $[\text{Na}_2\text{B}_4\text{O}_5(\text{OH})_4].8\text{H}_2\text{O}$
  • ✓
    $\text{Na}_2[\text{B}_4\text{O}_5(\text{OH)}_4].8\text{H}_2\text{O}$
  • C
    $[\text{Na}_2\text{B}_4\text{O}_5(\text{OH})_6].6\text{H}_2\text{O}$
  • D
    None of the above.
Answer
Correct option: B.
$\text{Na}_2[\text{B}_4\text{O}_5(\text{OH)}_4].8\text{H}_2\text{O}$
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MCQ 231 Mark
Which of the following is a water$-$borne disease:
  • A
    Malaria
  • ✓
    Dysentery
  • C
    Pneumonia
  • D
    Breathlessness
Answer
Correct option: B.
Dysentery
Water borne diseases are caused by micro organisma in untreated contaminated water.
ex. Cholera,Dysentery.
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MCQ 251 Mark
Which of the following elements can present both in cation and anion of its salts?
  • A
    $B$
  • ✓
    $Al$
  • C
    $Ga$
  • D
    $Tl$
Answer
Correct option: B.
$Al$
Boron can only form cation of its salts.
$Al$ can form both cation and anion of its salts.
Example: $\mathrm{Al}^3+ ($cation$) \mathrm{AlO}_3{ }^{3-} ($Anion$)$
$Ga$ and $Tl$ can only form cation of their salts.
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MCQ 261 Mark
Silicon is an important constituent of:
  • A
    Rocks.
  • ✓
    Amalgams.
  • C
    Chlorophyll.
  • D
    Haemoglobin.
Answer
Correct option: B.
Amalgams.
Silicon is an important constituent of rock in form of silica $\ce{SiO_2}$​.
Amalgams contains $Hg$.
Haemoglobin contains iron.
Chlorophyll contains $Mg$.
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MCQ 271 Mark
Apatite is an ore of:
  • ✓
    Fluorine.
  • B
    Chlorine.
  • C
    Bromine.
  • D
    Iodine.
Answer
Correct option: A.
Fluorine.
Apatite is $\mathrm{CaF}_2 \cdot 3 \mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2$​
$\therefore$ It is an ore of fluorine with calcium.
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MCQ 281 Mark
Which of the following does not exhibit inert pair effect?
  • A
    $Bi$
  • B
    $Pb$
  • ✓
    $B$
  • D
    $Tl$
Answer
Correct option: C.
$B$
Only high atomic weight elements in $p$ block show inert pair effect. Here $B$ is the first member of boron family and it does not have high atomic weight so it does not show inert pair effect.
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MCQ 291 Mark
The type of hybridisation of boron in diborane is:
  • A
    $sp.$
  • B
    $\ce{sp^2}$
  • ✓
    $\ce{sp^3}$
  • D
    $\mathrm{dsp}{ }^2$
Answer
Correct option: C.
$\ce{sp^3}$
Boron in diborane is $\ce{sp^3}$ hybridized.
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MCQ 301 Mark
Silica is heated with carbon in electric furnace to form :
  • A
    Silicon carbonate
  • ✓
    Silicon carbide or carborundum
  • C
    Silicon monoxide
  • D
    None
Answer
Correct option: B.
Silicon carbide or carborundum
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MCQ 311 Mark
Carbon has a unique ability to form pit$-$pt :
  • A
    Single bond,
  • B
    Double bond,
  • C
    Triple bond,
  • ✓
    Multiple bond,
Answer
Correct option: D.
Multiple bond,
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MCQ 321 Mark
Which of the following has highest dipole moment?
  • ✓
    $\mathrm{NH}_3$
  • B
    $\mathrm{NCI}_3$
  • C
    $\mathrm{NF}_3$
  • D
    $\mathrm{CO}_2$
Answer
Correct option: A.
$\mathrm{NH}_3$
$\mathrm{NH}_3$ has hightest dipole moment due to more polarity.
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MCQ 331 Mark
Rock crystal is :
  • A
    $\text{NaCl}$
  • B
    Sand
  • ✓
    Quartz
  • D
    Agate
Answer
Correct option: C.
Quartz
All clear colourless quartzs are known as rock crystal and they are used as ornamental stone.
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MCQ 341 Mark
Carbon dioxide can be obtained as a solid in the form of:
  • ✓
    Dry ice.
  • B
    Wet ice.
  • C
    Both $(a)$ and $(b)$
  • D
    None of these.
Answer
Correct option: A.
Dry ice.
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MCQ 351 Mark
The important mineral$(s)$ of $Al$ is$/$are:
  • A
    Bauxite.
  • B
    Cryolite.
  • ✓
    Both $(a)$ and $(b)$
  • D
    None of these.
Answer
Correct option: C.
Both $(a)$ and $(b)$
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MCQ 361 Mark
When aluminium is heated in the atmosphere of nitrogen it forms a nitride of formula :
  • ✓
    $\text{AlN}$
  • B
    $\mathrm{Al}_3 \mathrm{~N}$
  • C
    $\mathrm{AlN}_3$
    ​
  • D
    $\mathrm{Al}_2 \mathrm{~N}_3$​
Answer
Correct option: A.
$\text{AlN}$
When aluminium is heated in atmosphere of nitrogen it forms aluminum nitride and the reaction involve is.
$\text{2Al + N}_2\xrightarrow{\Delta}\text{2AlN}$
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MCQ 371 Mark
When Borax is heated with solid salt metal metaborate is produced. Which of the following reaction actually involve the metal metaborate formation?
  • ✓
    Acid base reaction between metal oxide and $\mathrm{B}_2 \mathrm{O}_3$

    ​
  • B
    Oxidation reduction reaction between metal oxide and $\mathrm{B}_2 \mathrm{O}_3$

    ​
  • C
    Substitution reaction between $\mathrm{NaBO}_2\  \&$ metal oxide
     
  • D
    Complex formation reaction between metal oxide and $\mathrm{B}_2 \mathrm{O}_3$​
Answer
Correct option: A.
Acid base reaction between metal oxide and $\mathrm{B}_2 \mathrm{O}_3$

​
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MCQ 381 Mark
The compounds of boron are :
  • A
    Mostly ionic
  • ✓
    Mostly covalent
  • C
    Both
  • D
    Crystalline
Answer
Correct option: B.
Mostly covalent
$IE$ and electron affinity values of boron are too high to form ionic compounds.
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MCQ 391 Mark
Which element does not show allotropy?
  • ✓
    $Pb$
  • B
    $Si$
  • C
    $C$
  • D
    $Sn$
Answer
Correct option: A.
$Pb$
$Pb$ orbitals are too diffused to form strong single $Pb-Pb$ bonds.
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MCQ 401 Mark
The tendency of $Ge, Sn$ and $Pb$ to show $+2$ oxidation state increases in the sequence:
  • A
    $\text{Ge=Sn < Pb}$
  • ✓
    $\text{Ge < Sn < Pb}$
  • C
    $\text{Ge > Sn > Pb}$
  • D
    $\text{Ge > Sn = Pb}$
Answer
Correct option: B.
$\text{Ge < Sn < Pb}$
The tendency of $\text{Ge, Sn, Pb}$ to show $+2$ oxidation state increases on moving from $Ge$ to $Pb.$ Thus, the correct sequence is $\text{Ge < Sn < Pb}.$
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MCQ 411 Mark
Boron possesses a high melting point among the elements of group$-13$ due to:
  • A
    Very high electronegativity of $B$.
  • B
    Very high ionisation energy of $B$.
  • C
    Small size of $B$.
  • ✓
    Strong bonding between individual atoms in the solid state.
Answer
Correct option: D.
Strong bonding between individual atoms in the solid state.
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MCQ 421 Mark
The blue coloured mineral 'Lapis Lazuli' which is used as a semi$-$precious stone is a mineral of the following class:
  • ✓
    Sodium alumino silicate
  • B
    Zinc cobaltate
  • C
    Basic copper carbonate
  • D
    Prussian blue
Answer
Correct option: A.
Sodium alumino silicate
Lapis Lazuli, a semi$-$precious stone is a "Sodium Alumino Silicate" class of mineral.
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MCQ 431 Mark
The strongest oxiding agent among the following is:
  • A
    $\mathrm{GeO}_2$
  • ✓
    $\mathrm{PbO}_2$
  • C
    $\mathrm{SrO}_2$
  • D
    $\mathrm{SiO}_2$
Answer
Correct option: B.
$\mathrm{PbO}_2$
$\text{PbO}_2\because \text{Pb}^{4+}+2\text{e}^-\rightarrow\text{Pb}^{2+}$ Which is more stable due to inert pair effect.
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MCQ 441 Mark
Which of the following element does not show inert pair effect?
  • A
    $Tl$
  • B
    $Pb$
  • C
    $Bi$
  • ✓
    $C$
Answer
Correct option: D.
$C$
The inert pair effect is the tendency of the electrons in the outermost atomic $s$ orbital to remain unionized or unshared in compounds of post$-$transition metals. The term inert pair effect is often used in relation to the increasing stability of oxidation states that are two less than the group valency for the heavier elements of groups $13, 14, 15$ and $16$. The inert pair effect is shown by $Tl, Pb$ and $Bi$ due to which, the lower oxidation state is more stable than the higher oxidation state. But $C$, being higher up in the periodic table, does not show inert pair effect.
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MCQ 451 Mark
Elements of group $14$ :
  • A
    Exhibit oxidation state of $+4$ only.
  • ✓
    Exhibit oxidation state of $+2$ and $+4.$
  • C
    Form $\mathrm{M}^{2-}$ and $\mathrm{M}^{4+}$ ions.
  • D
    Form $\mathrm{M}^{2+}$ and $\mathrm{M}^{4+}$ ions.
Answer
Correct option: B.
Exhibit oxidation state of $+2$ and $+4.$
Due to inert pair effect, elements of group $14$ exhibit oxidation states of $+2$ and $+4$. Thus, option $(b)$ is correct.
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MCQ 461 Mark
$\mathrm{H}_3 \mathrm{PO}_2$ is:
  • A
    Tribani.
  • B
    Dibasic.
  • ✓
    Monobasic.
  • D
    Tetrabasic.
Answer
Correct option: C.
Monobasic.
It is monobasic acid because it has one replacable hydrogen.
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MCQ 471 Mark
Super conductors are derived from compounds of:
  • ✓
    $p-$block elements
  • B
    lanthanides
  • C
    actinides
  • D
    transition elements
Answer
Correct option: A.
$p-$block elements
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MCQ 481 Mark
The exhibition of highest co$-$ordination number depends on the availability of vacant orbitals in the central atom. Which of the following elements is not likely to act as central atom in $\text{MF}^{3-}_6$?
  • ✓
    $B.$
  • B
    $Al.$
  • C
    $Ga.$
  • D
    $In.$
Answer
Correct option: A.
$B.$
Boron does not have $d-$orbittal. the element $M$ in the complex ion $\text{MF}^{3-}_6$has cordination number $6$. Boron can have maximum cordination number $4$. Thus, $B$ cannot from this complex.
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MCQ 491 Mark
The most abundant metal among the following is :
  • ✓
    $Al$
  • B
    $Ca$
  • C
    $Fe$
  • D
    $K$
Answer
Correct option: A.
$Al$
In the Earth's crust, aluminium is the most abundant $(8.3\%$ by weight$)$ metallic element and the third most abundant of all elements $($after oxygen and silicon$)$.
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MCQ 501 Mark
The geometry of a complex species can be understood from the knowledge of type of hybridisation of orbitals of central atom. The hybridisation of orbitals of central atom in $\ce{[Be(OH)^4]^-}$ and the geometry of the complex are respectively.
  • ✓
    $\mathrm{sp}^3$, tetrahedral.
  • B
    $\mathrm{sp}^3$, square planar.
  • C
    $\mathrm{sp}^3 \mathrm{~d}^2$, octahedral.
  • D
    $\ce{dsp^2}$, square planar.
Answer
Correct option: A.
$\mathrm{sp}^3$, tetrahedral.
Boron has die electronic configuration:
$1\text{s}^22\text{s}^22\text{p}^1_\text{x}2\text{p}^0_\text{y}2\text{p}^0_\text{z}$
In the excited state, $2s-$orbital electrons are impaired and one electron is shifted to a $p-$orbital. Now, hybridisation occurs between one $s-$and three $p-$orbitals to give $sp^3$ hybridisation and tetrahedral geometry.
$1\text{s}^2\underbrace{2\text{s}^12\text{p}^1_\text{x}2\text{p}^1_\text{y}2\text{p}^0_\text{z}}\\ \ \ \ \text{sp}^3\text{-hybridisation}$
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MCQ 511 Mark
Which of the following forms $\ce{M_2O}$ type of oxide?
  • A
    $Al$
  • B
    $B$
  • ✓
    $Tl$
  • D
    $Ca$
Answer
Correct option: C.
$Tl$
$Tl^+ ($due to inert pair effect$)$ is stable and forms compounds like $\ce{Tl_2​O}$.
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MCQ 521 Mark
What is the hybridisation of $C-$atom in $\ce{CO_2}$ molecule?
  • A
    $Sp ^2$
  • ✓
    $Sp$
  • C
    $S p^3$
  • D
    None of these.
Answer
Correct option: B.
$Sp$
${ \ \ \ \ \sigma\ \ \ \ \ \ \ \sigma}\\\text{O}=\text{C}=\text{O}: sp -$ hybridisation. $(\because2\sigma$ bonds$)$
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MCQ 531 Mark
Which one of the following is paramagnetic in nature?
  • ✓
    $NO$
  • B
    $\mathrm{N}_2 \mathrm{O}$
  • C
    $\mathrm{N}_2 \mathrm{O}_5$​
  • D
    All of the above
Answer
Correct option: A.
$NO$
Whenever two electrons are paired together in an orbital, or their total spin is $0$, they are diamagnetic electrons. Atoms with all diamagnetic electrons are called diamagnetic atoms.
A paramagnetic electron is an unpaired electron. $NO$ has one unpaired electron. Hence, it is paramagnetic in nature.
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MCQ 541 Mark
Which of the following compounds have zero dipole moment ?
  • ✓
    $\mathrm{BF}_3$
    ​
  • B
    $\mathrm{SnCl}_2$
    ​
  • C
    $\mathrm{H}_2 \mathrm{O}$
  • D
    $\mathrm{NH}_3$​
Answer
Correct option: A.
$\mathrm{BF}_3$
​
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MCQ 551 Mark
Which among the following substances is not a component of the mixture used for glazing pottery?
  • ✓
    Feldspar
  • B
    Silica
  • C
    Borax
  • D
    Alumina
Answer
Correct option: A.
Feldspar
Ceramic glaze is an impervious layer or coating of a vitreous substance which has been fused to a ceramic body through firing. Glaze can serve to colour, decorate or waterproof an item.
Pottery glaze is made up of five basic components. These components are silica, alumina, flux, colourants and modifiers.
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MCQ 561 Mark
An aqueous solution of borax is:
  • A
    Neutral.
  • B
    Amphoteric.
  • ✓
    Basic.
  • D
    Acidic.
Answer
Correct option: C.
Basic.
Borax is a salt of a strong base $\ce{(NaOH)}$ and a weak acid $(\mathrm{H}_3 \mathrm{BO}_3).$ It is, therefore, basic in nature.
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MCQ 571 Mark
Which of the following is used for making optical instruments:
  • ✓
    $\ce{SiO_2}$​
  • B
    $Si$
  • C
    $\ce{SiH_4}$​
  • D
    $\ce{SiC}$
Answer
Correct option: A.
$\ce{SiO_2}$​
Silica is an important ingredient in making glass, which is extensively used in making optical devices.
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MCQ 581 Mark
On commercial scale $CO$ is prepared by passage of steam over:
  • ✓
    Hot coke.
  • B
    Coal.
  • C
    Diamond.
  • D
    Graphite.
Answer
Correct option: A.
Hot coke.
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MCQ 591 Mark
Which of the following oxides dissolves in both hydrochloric acid and sodium hydroxide solution? $(1993)$
  • A
    $Na$
  • B
    $\ce{MgO}$
  • C
    $\ce{BaO}$
  • ✓
    $\mathrm{Al}_2 \mathrm{O}_3$​
Answer
Correct option: D.
$\mathrm{Al}_2 \mathrm{O}_3$​
$\mathrm{Al}_2 \mathrm{O}_3$​ is an amphoteric oxide.
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MCQ 601 Mark
Borax bead test is used to identify the:
  • A
    Anion in coloured salt
  • ✓
    Cation in coloured salt
  • C
    Anion in white salt
  • D
    Cation in white salt
Answer
Correct option: B.
Cation in coloured salt
Borax bead test is used to identify the coloured metal ions in given salt. The coloured metal ions form their corresponding metaborate with boron and their colour used to identify them.
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MCQ 611 Mark
$Ti^+$ is more stable than $TI^{3+}$ due to:
  • ✓
    Inert pair effect.
  • B
    Smaller size.
  • C
    Bigger size.
  • D
    Higher hydration energy.
Answer
Correct option: A.
Inert pair effect.
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MCQ 621 Mark
Which of the following reacts with nitrogen when heated in air:
  • ✓
    $Al$
  • B
    $C$
  • C
    $Na$
  • D
    $K$
Answer
Correct option: A.
$Al$
$\ce{2Al + N_2 ​\rightarrow 2AlN}$
Thus, $Al$ reacts with nitrogen when heated in air to form aluminium trinitride.
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MCQ 631 Mark
Electronic configuration of only one $p-$block element is exceptional. One molecule of that element consists of how many atoms of it?
  • ✓
    One
  • B
    Two
  • C
    Three
  • D
    Four
Answer
Correct option: A.
One
The electronic configuration of an only $p-$block element is exceptional. One molecule of that element consists of only one atom of it.
As the exception is found in only He, as helium has the electronic configuration to be $1s^2$. But other member of the same group has $\ce{ns^2np^6}$ configuration.
So, this is an exceptional case where He does not resemble its group in its configuration.
And as He is a noble gas element so it is monoatomic gas.
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MCQ 641 Mark
Which of the following metal forms a protective oxide layer to prevent corrosion?
  • A
    $Cu$
  • B
    $Mg$
  • ✓
    $Al$
  • D
    $Mn$
Answer
Correct option: C.
$Al$
$\mathrm{Al}_2 \mathrm{O}_3$​ is formed which forms a protective layer on the metal.
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MCQ 651 Mark
Which of the following oxides is acidic in nature?
  • ✓
    $ \mathrm{B}_2 \mathrm{O}_3 $
  • B
    $ \mathrm{Al}_2 \mathrm{O}_3$
  • C
    $ \mathrm{Ga}_2 \mathrm{O}_3 $
  • D
    $ \mathrm{In}_2 \mathrm{O}_3 $
Answer
Correct option: A.
$ \mathrm{B}_2 \mathrm{O}_3 $
$ \mathrm{B}_2 \mathrm{O}_3 $ is acidic in nature. It reacts with basic oxides to form metal borates. Acidic nature decreases on moving down the group.
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MCQ 661 Mark
Graphite conducts electricity due to the:
  • ✓
    Highly delocalised nature of $t-$electrons.
  • B
    Highly localised nature of $tt-$electrons.
  • C
    Highly polarised nature of $tt-$electrons.
  • D
    None of the above.
Answer
Correct option: A.
Highly delocalised nature of $t-$electrons.
Graphite conducts electricity due to the highly delocalised nature of $\pi -$electrons.
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MCQ 671 Mark
The hydrides of the first elements in groups $15 - 17$, namely $\ce{NH3​,H2​O}$ and $HF$ respectively, show abnormally high values for melting and boiling points. This is due to:
  • A
    Small size of $N, O$ and $F$
  • ✓
    The ability to form extensive intermolecular $H-$bonding
  • C
    The ability to form extensive intramolecular $H-$bonding
  • D
    Effective van der Waal's interaction
Answer
Correct option: B.
The ability to form extensive intermolecular $H-$bonding
The hydrides of the first elements in groups $15 - 17$, namely $\ce{NH_3​, H_2​O}$ and $HF$ respectively, show abnormally high values for melting and boiling points. This is due to the ability to form extensive inter$-$molecular $H-$bonding. In these hydrides, $H$ atom is attached to highly electronegative $N, O$ or $F$ atoms resulting in stronger hydrogen bonds which lead to molecular associations. Large amount of energy is needed to break these hydrogen bonds.
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MCQ 681 Mark
Which element has the highest valency with respect to oxygen?
  • A
    Sodium
  • B
    Aluminium
  • ✓
    Chlorine
  • D
    Sulphur
Answer
Correct option: C.
Chlorine
The valence of an element with respect to oxygen is twice the number of oxygen atoms with which one atom of that element chemically combines.
The valency of chlorine with respect to oxygen is $7$.
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MCQ 691 Mark
Elements of group $14$ used in semiconductors are:
  • A
    $\text{C, Si, Ge}$
  • B
    $\text{Si, Ge, Sn}$
  • ✓
    $\text{Si, Ge}$
  • D
    $\text{B, Si, Ge}$
Answer
Correct option: C.
$\text{Si, Ge}$
Silicon is found in the basis of all electronic devices. It is a semiconductor.
Germanium is another element used in semiconductors.
Ultrapure form of $Ge$ and $Si$ are used to make translators and semi conductors.
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MCQ 701 Mark
Cement, the important building material is a mixture of oxides of several elements. Besides calcium, iron and sulphur, oxides of elements of which of the group $(s)$ are present in the mixture?
  • A
    group $2$.
  • ✓
    groups $2, 13$ and $14$.
  • C
    groups $2$ and $13.$
  • D
    groups $2$ and $14.$
Answer
Correct option: B.
groups $2, 13$ and $14$.
Cement is manufactured by combining substances which are lime$\text{(CaO)}$, clay contains silica $\text{(SiO)}$ and oxides of $Al, Mg$ and iron.
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MCQ 711 Mark
Which of the following oxidation states are the most characteristic for lead and tin?
  • A
    $+2,+2$
  • B
    $+4,+2$
  • ✓
    $+2,+4$
  • D
    $+4,+4$
Answer
Correct option: C.
$+2,+4$
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MCQ 721 Mark
Reaction of ammonia with diborane gives initially $\mathrm{B}_2 \mathrm{H}_6 \cdot 2 \mathrm{NH}_3$ which on further heating gives:
  • ✓
    Borazine.
  • B
    Borax.
  • C
    Boric acid.
  • D
    All of these.
Answer
Correct option: A.
Borazine.
Reaction of ammonia with diborane gives initially $\mathrm{B}_2 \mathrm{H}_6 \cdot 2 \mathrm{NH}_3$ which is formulated as $\left[\mathrm{BH}_2\left(\mathrm{NH}_3\right)_2\right]^{+}$. $\left[\mathrm{BH}_4\right]^{-}$further heating gives borazine, $\mathrm{B}_3 \mathrm{N}_3 \mathrm{H}_6$ known as "inorganic benzene" in view of its ring structure with alternate $BH$ and $NH$ groups.
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MCQ 731 Mark
Which element froms maximum compound in chemistry?
  • A
    $O$
  • B
    $H$
  • C
    $Si$
  • ✓
    $C$
Answer
Correct option: D.
$C$
Carbon is the element which forms the highest number of compounds especially organic compounds due to its catenation $($long chain formation$)$ ability. Carbon, with $4$ valence atoms and by virtue of being small in size is most suited to form the highest number of compounds.
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MCQ 741 Mark
Which of the following is wrong about silica?
  • A
    Purest form of silica is know as quartz.
  • B
    Quartz is also know as rock crystal.
  • C
    Quartz contain hexagonal prisms.
  • ✓
    $U.V$. light cannot pass through quartz.
Answer
Correct option: D.
$U.V$. light cannot pass through quartz.
Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar. Its crystal structure is a continuous framework of $\ce{SiO_4}$ silicon$–$oxygen tetrahedral, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of $\ce{SiO_2}$. Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent, $U.V$. light can pass through quartz.
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MCQ 751 Mark
All group$-14$ members when heated in oxygen form:
  • A
    Monoxide.
  • B
    Dioxide.
  • C
    Trioxide.
  • ✓
    Monoxide and dioxide both.
Answer
Correct option: D.
Monoxide and dioxide both.
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MCQ 761 Mark
Among $\ce{III-A}$ group elements, the elements with highest and lowest $I.P$. values are:
  • A
    $B, Tl$
  • ✓
    $B, In$
  • C
    $B, Al$
  • D
    $B, Ga$
Answer
Correct option: B.
$B, In$
$I.P$. does not smoothly decrease down in $\text{III−A}$ group. The decrease from $B$ to $Al$ is associated with increase in size. The observed discontinuity in the $I.P.$ values between $Al$ and $Ga$, and between In and $Tl$ are due to the inability of $d-$ and $f-$electrons, which have low screening effect to compensate the increase in nuclear charge.
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MCQ 771 Mark
In the electrothermal process, the compound displaced by silica from calcium phosphate is:
  • A
    Calcium
  • B
    Phosphine
  • C
    Phosphorus
  • ✓
    Phosphorus pentoxide
Answer
Correct option: D.
Phosphorus pentoxide
In the electrothermal process, the compound displaced by silica from calcium phosphate is phosphorus pentoxide. It is then reduced by coke in electric furnace to get white phosphorus.
$\mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2+{ }_3 \mathrm{SiO}_2 \rightarrow{ }_3 \mathrm{CaSiO}_3+\mathrm{P}_2 \mathrm{O}_5$​
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MCQ 781 Mark
Anhydrous borax is:
  • ✓
    $ \mathrm{Na}_2 \mathrm{~B}_4 \mathrm{O}_7 $
  • B
    $\mathrm{Na}_2 \mathrm{~B}_4 \mathrm{O}_7 \cdot 5 \mathrm{H}_2 \mathrm{O} $
  • C
    $ \mathrm{Na}_2 \mathrm{~B}_4 \mathrm{O}_7 \cdot 10 \mathrm{H}_2 \mathrm{O} $
  • D
    $ \mathrm{Na}_2 \mathrm{~B}_4 \mathrm{O}_7 \cdot 8 \mathrm{H}_2 \mathrm{O} $
Answer
Correct option: A.
$ \mathrm{Na}_2 \mathrm{~B}_4 \mathrm{O}_7 $
Anhydrous borax has formula $ \mathrm{Na}_2 \mathrm{~B}_4 \mathrm{O}_7 $​.
Anhydrous means no water of crystallisation.
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MCQ 791 Mark
For which of the following reactions, is Gay Lussac's law not applicable?
  • A
    Formation of HI from its constituents
  • B
    Formation of $\mathrm{NH}_3$ from its constituents
  • ✓
    Formation of $\mathrm{CO}_2$ from its constituents
  • D
    Formation of $\mathrm{SO}_3$ from $\mathrm{SO}_2$ and $\mathrm{O}_2$​
Answer
Correct option: C.
Formation of $\mathrm{CO}_2$ from its constituents
Gay Lussac's law not applicable to formation of $\ce{CO_2}$​ from its constituents as carbon and oxygen exist in different physical states.
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MCQ 801 Mark
The structure of silicon$(IV)$ oxide belongs to the type:
  • A
    Ionic lattice
  • B
    Macromolecular, with a layer structure
  • C
    Molecular lattice, with van der Waals forces among the molecules
  • ✓
    Macromolecular, with a non$-$layer structure
Answer
Correct option: D.
Macromolecular, with a non$-$layer structure
$\text{Si(IV)}$ oxide is macromolecular with a non layer structure similar to diamond.
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MCQ 811 Mark
Stannite is an ore of $.........$
  • ✓
    Tin
  • B
    Lead
  • C
    Germanium
  • D
    Carbon
Answer
Correct option: A.
Tin
Stannite is a mineral, a sulfide of copper, iron, and tin. The chemical formula $\mathrm{Cu}_2 \mathrm{FeSnS}_4$.​
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MCQ 821 Mark
Which of the following property does not support anamolous behaviour of boron?
  • A
    Small size
  • B
    High electronegativity
  • C
    High ionization energy
  • ✓
    Formation of trihalides
Answer
Correct option: D.
Formation of trihalides
Formation of trihalides does not support anomalous behaviour of boron as other elements of boron family also form trihalides such as $\ce{AlCl_3}$​.
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MCQ 831 Mark
Which of the following is most metallic:
  • A
    $B$
  • B
    $Al$
  • C
    $Mg$
  • ✓
    $K$
Answer
Correct option: D.
$K$
$K$ is most metallic due to lowest ionisation enthalpy.
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MCQ 841 Mark
Borax bead test is responded by:
  • A
    Divalent metals
  • B
    Heavy metals
  • C
    Light metal
  • ✓
    Metals which form coloured metaborates
Answer
Correct option: D.
Metals which form coloured metaborates
When the glossy bead is dipped in metal oxide and heated, the corresponding metal metaborates are formed.
The characteristic colour of these metaborates enables us to identify the metal.
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MCQ 851 Mark
Glass reacts with $HF$ forming :
  • A
    $\mathrm{F}_2$
  • ✓
    $\mathrm{H}_2 \mathrm{SiF}_6$
  • C
    $\mathrm{CaF}_2$
  • D
    $\ce{NaF}$
Answer
Correct option: B.
$\mathrm{H}_2 \mathrm{SiF}_6$
$\mathrm{SiO}_2+6 \mathrm{HF} \rightarrow \mathrm{H}_2 \mathrm{SiF}_6+2 \mathrm{H}_2 \mathrm{O}$
When glass reacts with $HF, \mathrm{H}_2 \mathrm{SiF}_6$​ is formed.
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MCQ 861 Mark
$\mathrm{SnCl}_2$ is good:
  • ✓
    Reducing agent.
  • B
    Oxidising agent.
  • C
    Bleaching agent.
  • D
    Dehydrating agent.
Answer
Correct option: A.
Reducing agent.
$\text{SnCl}_2+\text{2FeCl}_3\xrightarrow{\ \ \ \ \ \ \ \ }2\text{FeCl}_2+\text{SnCl}_4$
$\mathrm{SnCl}_2$ is good reducing agent.
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MCQ 871 Mark
In which of the following the inert pair effect is most prominent ?
  • A
    $C$
  • B
    $Ge$
  • C
    $Si$
  • ✓
    $Pb$
Answer
Correct option: D.
$Pb$
Due to poor or ineffective shielding of the $ns^2$ electrons of the valence shell by intervening d$-$ and f$-$electrons, the $s-$electrons are reluctant to participate in bond formation.
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MCQ 881 Mark
$\ce{CO_2}$ is gas, while $\ce{SiO_2}$ is solid because:
  • A
    $\mathrm{CO}_2$ is a linear molecule, while $\mathrm{SiO}_2$ is angular.
  • B
    van der Waals' forces are very strong in $\mathrm{SiO}_2$.
  • C
    $\mathrm{CO}_2$ is covalent, while $\mathrm{SiO}_2$ is ionic.
  • ✓
    $Si$ cannot form stable bonds with $O$, hence $Si$ has to form a $3D$ lattice.
Answer
Correct option: D.
$Si$ cannot form stable bonds with $O$, hence $Si$ has to form a $3D$ lattice.
$\ce{SiO_2}$ is solid because $Si$ cannot form stable bonds with $O$, hence $Si$ has to form a $3D$ lattice of $\ce{SiO_2}$ molecules and form solid structure.
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MCQ 891 Mark
Which of the following is$/$are allotrope$(s)$ of carbon?
  • A
    Diamond.
  • B
    Graphite.
  • C
    Fullerene.
  • ✓
    All of these.
Answer
Correct option: D.
All of these.
Diamond, graphite and fullerene are the allotropes of carbon.
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MCQ 901 Mark
A compound $X$, of boron reacts with $\ce{NH_3}$ on heating to give another compound $Y$ which is called inorganic benzene. The compound $X$ can be prepared by treating $\ce{BF_3}$ with Lithium aluminium hydride. The compounds $X$ and $Y$ are represented by the formulas.
  • ✓
    $ \mathrm{B}_2 \mathrm{H}_6, \mathrm{~B}_3 \mathrm{~N}_3 \mathrm{H}_6 $
  • B
    $ \mathrm{~B}_2 \mathrm{O}_3, \mathrm{~B}_3 \mathrm{~N}_3 \mathrm{H}_6 $
  • C
    $ \mathrm{BF}_3, \mathrm{~B}_3 \mathrm{~N}_3 \mathrm{H}_6 $
  • D
    $ \mathrm{~B}_3 \mathrm{~N}_3 \mathrm{H}_6, \mathrm{~B}_2 \mathrm{H}_6 $
Answer
Correct option: A.
$ \mathrm{B}_2 \mathrm{H}_6, \mathrm{~B}_3 \mathrm{~N}_3 \mathrm{H}_6 $
A compound $X$, of boron reacts with $NH_3$ on heating to give another compound $Y$ which is called inorganic benzene.
$ \ \ \ \ \ \ 3\text{B}_2\text{H}_6+6\text{NH}_3\rightarrow3[\text{BH}_2(\text{NH}_3)_2]^+[\text{BH}^4]^-\\ \ \ \ \ \ \ \ \ \ \ \ \ \text{(x)} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \downarrow \text{heat}\\ \ \ \ \ \ \ \ \ ^\text{Diborane}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2\text{B}_3\text{N}_3\text{H}_6+12\text{H}_2 \\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{(Y)}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Borazole/ Inorganic benzene}\\4\text{BF}_3+3\text{LiAlH}_4\xrightarrow{ \ \ \ \ \ \ \ \ \ }2\text{B}_2\text{H}_6+3\text{LiF}+3\text{AIF}_3\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{(x)}$
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MCQ 911 Mark
The most abundant $\text{IVA}$ group elements in the earth's crust is:
  • ✓
    Germanium
  • B
    Carbon
  • C
    Silicon
  • D
    Tin
Answer
Correct option: A.
Germanium
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MCQ 921 Mark
Which of the following member of the carbon family does not have an allotrope?
  • A
    $Si$
  • B
    $Sn$
  • C
    $C$
  • ✓
    $Ge$
Answer
Correct option: D.
$Ge$
In carbon family only carbon, silicon and tin forms allotrope. Carbon has multiple allotrope, Silicon has two known allotropes that exist at room temperature and Tin also has two allotropes.Ge does not have an allotrope.
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MCQ 931 Mark
Percentage of lead in lead pencil is:
  • ✓
    $0$
  • B
    $20$
  • C
    $80$
  • D
    $60$
Answer
Correct option: A.
$0$
It is made up of graphite
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MCQ 941 Mark
Borax is used as cleansing agent because on dissolving in water it forms:
  • ✓
    Alkaline solution.
  • B
    Acidic solution.
  • C
    Bleaching solution.
  • D
    Colloidal solution.
Answer
Correct option: A.
Alkaline solution.
$\text{Na}_2\text{B}_4\text{O}_7:10\text{H}_2\text{O}+6\text{H}_2\text{O}\rightarrow\\2\text{NaOH}+4\text{H}_3\text{BO}_3+10\text{H}_2\text{O}\\\ \ ^\text{(Strong)}\ \ \ \ \ \ \ ^\text{(Weak)}$
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MCQ 951 Mark
Dry ice is:
  • A
    Solid $\mathrm{NH}_3$.
  • B
    Solid $\mathrm{SO}_2$.
  • ✓
    Solid $\mathrm{CO}_2$.
  • D
    Solid $\mathrm{N}_2$.
Answer
Correct option: C.
Solid $\mathrm{CO}_2$.
Solid $\mathrm{CO}_2$ is called dry ice becaouse it is used for making ice bath for organic reaction in laboratory. It is prepared by cooling $\mathrm{CO}_2$ gas at high pressure.
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MCQ 961 Mark
The tendency to behave as Lewis acid decreases as the size:
  • ✓
    Increases.
  • B
    Decreases.
  • C
    Remains same.
  • D
    First increases then decreases.
Answer
Correct option: A.
Increases.
The tendency to behave as a Lewis acid decreases with the increase in the size on moving down the group.
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MCQ 971 Mark
Xenon hexafluoride reacts with silica to form a xenon compound $X$. The oxidation state of $Xe$ in $X$ is :
  • A
    $+2$
  • B
    $+4$
  • ✓
    $+6$
  • D
    $0$
Answer
Correct option: C.
$+6$
$\mathrm{SiO}_2+2 \mathrm{XeF}_6 \rightarrow 2 \mathrm{XeOF}_4+\mathrm{SiF}_4$​
Oxidation state of $Xe$ in $(X)$ is $+ 6$
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MCQ 981 Mark
Boric acid is not a protonic acid but it acts as a Lewis acid by:
  • ✓
    Accepting electrons from a hydroxyl ion.
  • B
    Donating electrons to a chloride ion.
  • C
    Donating electrons to a proton.
  • D
    Accepting proton from water.
Answer
Correct option: A.
Accepting electrons from a hydroxyl ion.
Boric acid is not a protonic acid, but it acts as a Lewis acid by accepting electrons from a hydroxyl ion.
$\text{B(OH)}_3+2\text{HOH}\xrightarrow{\ \ \ \ \ \ \ }[\text{B}(\text{OH})_4]^-+\text{H}_3\text{O}^+$.
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MCQ 991 Mark
Which statement is correct with respect to the property of the elements with increase in atomic number in the carbon family?
  • A
    Their metallic character decreases
  • ✓
    The stability of $+2$ oxidation state increases
  • C
    Their ionization energy increases
  • D
    Their atomic size decreases
Answer
Correct option: B.
The stability of $+2$ oxidation state increases
Due to the inert pair effect, as we move down the group, lower oxidation state becomes more stable, so stability of $2+$ oxidation state increases.
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MCQ 1001 Mark
Which of the following elements has a limited co$-$ordination number of four?
  • A
    $Sn$
  • ✓
    $C$
  • C
    $Si$
  • D
    $Ge$
Answer
Correct option: B.
$C$
Tin, silicon and germanium can extend their valency owing to the empty $d$ orbitals present in their configuration. However, Carbon cannot do so.
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MCQ 1011 Mark
Carbon has no tendency to form complex compounds due to:
  • A
    Its small size.
  • B
    The availability of vacant $d-$orbitals.
  • ✓
    Non$-$availability of vacant $d-$orbitals.
  • D
    No tendency to form covalent bonds.
Answer
Correct option: C.
Non$-$availability of vacant $d-$orbitals.
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MCQ 1021 Mark
The most commonly used reducing agent is:
  • A
    $\mathrm{AlCl}_3$
     
  • B
    $\mathrm{PbCl}_2$.
  • C
    $\mathrm{SnCl}_4$.
  • ✓
    $\mathrm{SnCl}_2$
Answer
Correct option: D.
$\mathrm{SnCl}_2$
$+4$ oxidation state of $Sn$ is more stable than $+2$ oxidation state. Therefore, $\ce{Sn^{2+}}$ can be easily oxidised to $\ce{Sn^{4+}}$ and hence $\ce{SnCl_2}$ acts a reducing agent.
$\text{SnCl}_2+2\text{Cl}\rightarrow\text{SnCl}_4+2\text{e}^-$
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MCQ 1031 Mark
Which of the following statements is incorrect?
  • A
    Aluminium is a bright silvery$-$white metal.
  • B
    Aluminium forms alloys with $\text{Cu, Mn, Mg, Si}$ and $\text{Zn.}$
  • ✓
    The use of aluminium and its compounds for domestic purposes is now increased considerably.
  • D
    Both $(a)$ and $(b).$
Answer
Correct option: C.
The use of aluminium and its compounds for domestic purposes is now increased considerably.
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MCQ 1041 Mark
Which of the following is used to convert alcohol to petroleum directly?
  • ✓
    $\text{ZSM}-5$
  • B
    $\text{Fe}_2\text{O}_3$
  • C
    $\text{Cr}_2\text{O}_3/ \text{Al}_2\text{O}_3$
  • D
    Feldspar
Answer
Correct option: A.
$\text{ZSM}-5$
$\text{Alcohol}\xrightarrow{\text{ZSM-5}}\text{Petroleum}$
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MCQ 1051 Mark
Oxidation of aluminium is:
  • ✓
    Reversible
  • B
    Exothermic
  • C
    Endothermic
  • D
    Slow reaction
Answer
Correct option: A.
Reversible
$Al$ has a strong affinity for $O_2$​. Oxidation of $Al$ is a reaction of negative enthalpy$($exothermic$)$.
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MCQ 1061 Mark
Borax bead test is not used to identify cation in:
  • A
    Cobalt salt
  • B
    Nickel salt
  • ✓
    Aluminium salt
  • D
    Copper salt
Answer
Correct option: C.
Aluminium salt
Aluminium forms colourless metaborate and thus gives an indecisive test.
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MCQ 1071 Mark
Which one of the following is the correct statement?
  • A
    Beryllium exhibits coordination number of six
  • ✓
    Chlorides of both beryllium and aluminium have bridged chloride structures in solid phase
  • C
    $\mathrm{B}_2 \mathrm{H}_6 \cdot 2 \mathrm{NH}_3$​ is known as 'inorganic benzene'
  • D
    Boric acid is a protonic acid
Answer
Correct option: B.
Chlorides of both beryllium and aluminium have bridged chloride structures in solid phase
$Be$ and $Al$ are diagonally related with each other and chlorides of both beryllium and aluminium have bridged chloride structures in the solid phase.
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MCQ 1081 Mark
Most covalent halide of aluminium is:
  • A
    Aluminium bromide
  • B
    Aluminium fluoride
  • ✓
    Aluminium iodide
  • D
    Aluminium chloride
Answer
Correct option: C.
Aluminium iodide
Due to higher polarisibility, iodide is most covalent by Fajan's rule.
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MCQ 1091 Mark
Boron compounds behave as Lewis acids because of their :
  • A
    Acidic nature.
  • B
    Covalent nature.
  • C
    Ionic nature.
  • ✓
    Vacant orbital.
Answer
Correct option: D.
Vacant orbital.
A Lewis acid is an electron pair acceptor, while Lewis base is an electron pair donor.
Boron compounds behave as Lewis acids because of their vacant orbital. Its octet is incomplete, in which boron can accept an electron pair.
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MCQ 1101 Mark
Self protective metal among the following is:
  • A
    $Na$
  • ✓
    $Al$
  • C
    $Fe$
  • D
    $K$
Answer
Correct option: B.
$Al$
$Al$ when comes in contact with air to form $\mathrm{Al}_2 \mathrm{O}_3$​ which forms a protective passive layer on the metal. This layer cannot be removed by chemical means.
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MCQ 1111 Mark
The material used in solar cell contains :
  • A
    $Cs$
  • ✓
    $Si$
  • C
    $Sn$
  • D
    $T$
Answer
Correct option: B.
$Si$
Silicon is a semicoductor and is used in solar cells, sometimes doped.
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MCQ 1121 Mark
Boric acid is acid because its molecule:
  • A
    Contamp replaceable $H^+$.
  • B
    Gives up proton.
  • ✓
    Accepts $\ce{OH^-}$ from water and releases proton.
  • D
    Combines with proton from water molecule.
Answer
Correct option: C.
Accepts $\ce{OH^-}$ from water and releases proton.
$\text{B(OG})_4+\text{H}_2\text{O}\rightarrow\text{B(OH)}^-_4+\text{H}^+$
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MCQ 1131 Mark
A orange solid $'X'$ on heating gives green reside, a gas non$-$supporter of combustion and water. Identify $X$ :
  • ✓
    $\left(\mathrm{NH}_4\right)_2 \mathrm{Cr}_2 \mathrm{O}_7$
  • B
    $\mathrm{CaCO}_3$
  • C
    $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7 $
  • D
    $\mathrm{KMnO}_4$
Answer
Correct option: A.
$\left(\mathrm{NH}_4\right)_2 \mathrm{Cr}_2 \mathrm{O}_7$
$(\text{NH}_4)_2\text{Cr}_2\text{O}_7\xrightarrow{\ \ \ \text{o}\ \ \ }\text{N}_2+4\text{H}_2\text{O}+\text{Cr}_2\text{O}_3\\ \ \ \ \ \ \ \ ^\text{(orange)}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ^\text{(green)}$
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MCQ 1141 Mark
Aqueous solution of borax is $.........$ in nature:
  • A
    Neutral
  • B
    Acidic
  • ✓
    Alkaline
  • D
    None
Answer
Correct option: C.
Alkaline
The aqueous solution is alkaline due to hydrolysis resulting into the formation of strong base $\ce{NaOH}$ and weak acid tetraboric acid.
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MCQ 1151 Mark
Quartz is extensively used as a piezoelectric material, it contains $.........$
  • A
    $Pb.$
  • ✓
    $Si.$
  • C
    $Ti.$
  • D
    $Sn.$
Answer
Correct option: B.
$Si.$
Quartz is one of the crystalline from of silica and at high temprature can be converted into other crystalline forms. It is extensively used as apiezoelectric material.
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MCQ 1161 Mark
The oxidation state of the most electronegative element in the products of the reaction $\ce{BaO_2}$​ with $\ce{H_2​SO_4}$​ are :
  • A
    $0$ and $-1$
  • B
    $-2$ and $+1$
  • ✓
    $-1$ and $-2$
  • D
    $-2$ and $0$
Answer
Correct option: C.
$-1$ and $-2$
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MCQ 1171 Mark
The basic structural units of silicates is:
  • ✓
    $\text{SiO}^{2-}_3$
  • B
    $\text{SiO}^{2-}_4$
  • C
    $\text{SiO}^-$
  • D
    $\text{SiO}^{4-}_4$
Answer
Correct option: A.
$\text{SiO}^{2-}_3$
$\text{SiO}^{4-}_4$ is basic structural unit of silicates.
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MCQ 1181 Mark
Boron forms $\text{BX3}$​ type of halides. The correct decreasing order of Lewis$-$acid strength of these halides is:
  • A
    $ \mathrm{BF}_3>\mathrm{BCl}_3>\mathrm{BBr}_3>\mathrm{BI}_3 $
    ​
  • ✓
    $ \mathrm{BI}_3>\mathrm{BBr}_3>\mathrm{BCl}_3>\mathrm{BF}_3 $
    ​
  • C
    $ \mathrm{BF}_3>\mathrm{BI}_3>\mathrm{BCl}_3>\mathrm{BBr}_3 $
    ​
  • D
    $ \mathrm{BF}_3>\mathrm{BCl}_3>\mathrm{BI}_3>\mathrm{BBr}_3 $​
Answer
Correct option: B.
$ \mathrm{BI}_3>\mathrm{BBr}_3>\mathrm{BCl}_3>\mathrm{BF}_3 $
​
The decreasing order of the Lewis acidity of boron halides is $\mathrm{BI}_3>\mathrm{BBr}_3>\mathrm{BCl}_3>\mathrm{BF}_3 $.
This order is due to the relative tendency of the halogen atom to back donate its unutilized electrons to the vacant p-orbitals of boron atom.
Due to the back donation of electrons from fluorine to boron, the electron deficiency of boron is reduced and hence, Lewis acidity is decreased.
The tendency for the formation of back bonding is maximum in boron trifluoride and decreases very rapidly from boron trifluoride to boron triodide.
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MCQ 1191 Mark
Which of the following does not exist ?
  • A
    $\ce{BiCl_5}$​
  • B
    $\ce{XeH_4}$​
  • C
    $\ce{BiF_5}$​
  • ✓
    Both $(A)$ and $(B)$
Answer
Correct option: D.
Both $(A)$ and $(B)$
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MCQ 1201 Mark
Following are the figures of two different allotropes of carbon. Identify these allotropes from the following options.
  • A
    $A \rightarrow$ Graphite; $B \rightarrow$ Diamond.
  • ✓
    $A \rightarrow$ Diamond; $B \rightarrow$ Graphite.
  • C
    $A \rightarrow$ Graphite; $B \rightarrow$ Fullerene.
  • D
    $A \rightarrow$ Diamond; $B \rightarrow$ Fullerene.
Answer
Correct option: B.
$A \rightarrow$ Diamond; $B \rightarrow$ Graphite.
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MCQ 1211 Mark
The maxium covalency of aluminium is:
  • A
    $4$
  • ✓
    $6$
  • C
    $8$
  • D
    $3$
Answer
Correct option: B.
$6$
The maximum covalency of Aluminium is $6$. Since Aluminium belongs to the $3^{rd}$ period, it possesses a $3d$ subshell as well. As a cation it can use $\ce{sp^3d^2}$ hybrid orbitals for a covalency of $6$.
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MCQ 1221 Mark
Crystalline boron in small amounts may be obtained by :
  • A
    Reducing $\mathrm{BCl}_3$ with $\mathrm{H}_2$
  • B
    pyrolysis of $\mathrm{BI}_3$
  • C
    thermal decomposition of diborane
  • ✓
    all of these
Answer
Correct option: D.
all of these
Crystalline boron is obtained by reducing volatile boron halides with hydrogen at high temperatures. Ultrapure boron for use in semiconductor industry is produced by the decomposition of diborane at high temperature and then purified with the zone melting process.
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MCQ 1231 Mark
Aluminium oxide is not reduced by chemical reactions since :
  • A
    Aluminium oxide is reactive.
  • B
    Reducing agent contaminate
  • ✓
    Aluminium oxide is highly stable
  • D
    Process polutes the environment.
Answer
Correct option: C.
Aluminium oxide is highly stable
Aluminium oxide is not reduced by chemical reactions since aluminium oxide is most stable and it does not gain electrons from any reducing agent.
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MCQ 1241 Mark
An element $R$ belongs to $\text{III A}$ group. Which is true with respect to $R$?
  • A
    It is a gas at room temperature
  • B
    It has an oxidation state of $+4$
  • ✓
    It forms an oxide of the type $\mathrm{R}_2 \mathrm{O}_3$
  • D
    It forms a halide of the type $\mathrm{Rx}_2$​
Answer
Correct option: C.
It forms an oxide of the type $\mathrm{R}_2 \mathrm{O}_3$
An $\text{III A}$ group element has valency $3$.
So they form an oxide of type $\mathrm{R}_2 \mathrm{O}_3$​.
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MCQ 1251 Mark
The color imparted by $\text{Co(Il)}$ compounds to glass is:
  • ✓
    Deep blue.
  • B
    Green.
  • C
    Yellow.
  • D
    Red.
Answer
Correct option: A.
Deep blue.
Cobalt primarily used as the metal, in the preparation of magnetic, wear$-$resistant and high$-$strength alloys.
The color imparted by $\text{Co(Il)}$ compounds to glass is deep blue.
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MCQ 1261 Mark
Which of the following is not correct ?
  • A
    Anhydrous $\mathrm{AlCl}_3$ exists as $\mathrm{Al}_2 \mathrm{Cl}_6$
  • B
    Anhydrous $\mathrm{AlCl}_3$ sublimes on heating
  • C
    Anhydrous $\mathrm{AlCl}_3$ fumes in air
  • ✓
    Anhydrous $\mathrm{AlCl}_3$ is ionic
Answer
Correct option: D.
Anhydrous $\mathrm{AlCl}_3$ is ionic
All statements are correct except that $\mathrm{AlCl}_3$​ is covalent in anhydrous form and its aqueous solution is ionic in nature.
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MCQ 1271 Mark
Silicon is the $.........$ abundant element in the earth's crust:
  • A
    most
  • ✓
    $2^{nd}$ most
  • C
    $3^{rd}$ most
  • D
    none of these
Answer
Correct option: B.
$2^{nd}$ most
Silicon is the second $(27.7\%$ by mass$)$ most abundant element in the earth's crust.
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MCQ 1281 Mark
Which of the element shows $+4$ oxidation state?
  • ✓
    $Sn$
  • B
    $Ra$
  • C
    $Fr$
  • D
    $Sc$
Answer
Correct option: A.
$Sn$
Only tin is capable of exhibiting stable $+4$ oxidation state while others cannot. $\mathrm{Sn}^{+4}$ state is stable and forms $\mathrm{SnCl}_4$ compound.
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MCQ 1291 Mark
Which of these forms nitride with nitrogen at higher temperature?
  • A
    Aluminium
  • B
    Boron
  • ✓
    Both $A$ and $B$
  • D
    Indium
Answer
Correct option: C.
Both $A$ and $B$
Aluminium and boron forms nitride with nitrogen at higher temperature due to the high bond energy of nitrogen. In case of aluminium, a thin oxide layer is formed so it also needs high temperature to react with nitrogen to form the nitride.
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MCQ 1301 Mark
An element $'X'$ atomic number $51$ belongs to $.........$
  • A
    $S-$block
  • ✓
    $P-$block
  • C
    $D-$block
  • D
    $F-$block
Answer
Correct option: B.
$P-$block
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MCQ 1311 Mark
The form of $\mathrm{SiO}_2$ used as piezoelectric material:
  • A
    Cristobalite
  • ✓
    Quartz
  • C
    Kiesulguhr
  • D
    Silica gel
Answer
Correct option: B.
Quartz
Quartz crystals have piezoelectric properties; they develop an electric potential upon the application of mechanical stress. An early use of this property of quartz crystals was in phonograph pickups. One of the most common piezoelectric uses of quartz today is as a crystal oscillator. The quartz clock is a familiar device using the mineral. The resonant frequency of a quartz crystal oscillator is changed by mechanically loading it, and this principle is used for very accurate measurements of very small mass changes in the quartz crystal microbalance and in thin film monitors.
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MCQ 1321 Mark
Why $\mathrm{Bi}^{3+}$ more stable than $\mathrm{Bi}^{+5}$ ?
  • ✓
    Due to inert pair effect
  • B
    Due to inert gas electronic configuration
  • C
    Due to half filled configuration
  • D
    Due to lanthanide Contraction
Answer
Correct option: A.
Due to inert pair effect
$\mathrm{Bi}^{3+}$is more stable than $\ce{Bi^{5+}}$ due to inert pair effect. Ongoing down the group, inert pair effect increases due to more penetration of $s-$ orbital in nucleus due to which element tends to show lower oxidation state more stable than higher oxidation state. Thus, bismuth will show a strong tendency to change into $+3$ state from $+5$ state.
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MCQ 1331 Mark
Which of the following forms vortex ring?
  • ✓
    $\mathrm{P}_2 \mathrm{O}_5$
    ​
  • B
    $ \mathrm{PH}_3 $
    ​
  • C
    $ \mathrm{NH}_3$
    ​
  • D
    $ \mathrm{P}_2 \mathrm{O}_{10}$​
Answer
Correct option: A.
$\mathrm{P}_2 \mathrm{O}_5$
​
Phosphine forms vortex rings of $\mathrm{P}_2 \mathrm{O}_5$​ when it comes in contact of air. These rings are in form of white smoke.
$\therefore$ They are used in making smoke screens in warfare.
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MCQ 1341 Mark
Which is the crystalline form of silica?
  • A
    Agate
  • B
    Jaspar
  • C
    Onyx
  • ✓
    Crystobalite
Answer
Correct option: D.
Crystobalite
Silica $\ce{(SiO_2)}$​ occurs in various crystallographic forms such as quartz, crystobalite and tridymite that are interconvertible at suitable temperatures.
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MCQ 1351 Mark
Aqueous tension is the vapour pressure of water and depends only upon temperature: If the statement is true enter $1$, else enter $0$ :
  • ✓
    $1$
  • B
    $0$
  • C
    Both $A$ and $B$
  • D
    None of these
Answer
Correct option: A.
$1$
Aqueous tension is defined as the partial pressure of the water vapour present in the moist gas. Aqueous pressure exerted by a gas at particular temperature and it depends upon temperature.
The pressure exerted by moist gas $=$ pressure exerted by dry gas $+$ pressure of water vapour $($aqueous tension$)$.
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MCQ 1361 Mark
The relationship between first, second and third ionisation enthalpies of each group$-13$ element is:
  • A
    $\Delta_\text{i}\text{H}_\text{1}>\Delta_\text{i}\text{H}_2>\Delta_\text{i}\text{H}_3$
  • ✓
    $\Delta_\text{i}\text{H}_\text{1}<\Delta_\text{i}\text{H}_2<\Delta_\text{i}\text{H}_3$
  • C
    $\Delta_\text{i}\text{H}_1=\Delta_\text{i}\text{H}_2=\Delta_\text{i}\text{H}_3$
  • D
    $\Delta_\text{i}\text{H}_3<\Delta_\text{i}\text{H}_1<\Delta_\text{i}\text{H}_2$
Answer
Correct option: B.
$\Delta_\text{i}\text{H}_\text{1}<\Delta_\text{i}\text{H}_2<\Delta_\text{i}\text{H}_3$
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MCQ 1371 Mark
$\ce{BF_3}$ easily reacts with Lewis base such as $\ce{NH_3}$ to complete octet around boron. This can be expressed as:
  • ✓
    $\text{F}_3\text{B}\ +:\text{NH}_{3} \xrightarrow{\ \ \ \ \ }\text{F}_3\text{B}\leftarrow\text{NH}_3$
  • B
    $\text{F}_3\text{B}+:\text{NH}_3\xrightarrow{\ \ \ \ \ }\text{F} _3\text{B}\rightarrow\text{NH}_3$
  • C
    $:\text{BF}_3+\text{NH}_3\xrightarrow{\ \ \ \ \ \ \ \ }\text{BF}_3\rightarrow\text{NH}_3$
  • D
    $:\text{BF}_3+\text{NH}_3\xrightarrow{\ \ \ \ \ \ \ }\text{BF}_3\leftarrow\text{NH}_3$
Answer
Correct option: A.
$\text{F}_3\text{B}\ +:\text{NH}_{3} \xrightarrow{\ \ \ \ \ }\text{F}_3\text{B}\leftarrow\text{NH}_3$
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MCQ 1381 Mark
At standard conditions $.........$ has an allotropic form that is a good electrical conductor:
  • ✓
    Carbon
  • B
    Nitrogen
  • C
    Neon
  • D
    Argon
Answer
Correct option: A.
Carbon
Carbon has an allotrope known as Graphite. Graphite is a very good conductor of electricity. It can conduct electricity due to the presence of delocalized free electron.
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MCQ 1391 Mark
Which of the following is used to make transistor and semiconductor devices?
  • A
    Ultrapure form of germanium.
  • B
    Ultrapure form of silicon.
  • ✓
    Both $(a)$ and $(b)$.
  • D
    Neither $(a)$ nor $(b)$.
Answer
Correct option: C.
Both $(a)$ and $(b)$.
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MCQ 1401 Mark
Halides of $\ce{III A}$ group elements predominantly act as :
  • A
    Lewis bases
  • ✓
    Lewis acids
  • C
    Arrhenius acids
  • D
    Neutral halides
Answer
Correct option: B.
Lewis acids
In a trivalent state, the number of electrons around the central atom in a molecule of the compounds of these elements will be only six. Such electron deficient molecules have a tendency to accept a pair of electrons to achieve octet and thus behave as Lewis acids.
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MCQ 1411 Mark
Pnicogens are the elements of group:
  • ✓
    $15$
  • B
    $13$
  • C
    $\text{VIII}$
  • D
    Zero
Answer
Correct option: A.
$15$
Members of group $15$ or $VA$ of Periodic Table are called pnicogens. They include $\text{N, P, As, Sb}$ and $\text{Bi}.$
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MCQ 1421 Mark
Boric acid is polymeric due to:
  • A
    Its acidic nature.
  • ✓
    The presence of hydrogen bonds.
  • C
    Its monobasic nature.
  • D
    Its geometry.
Answer
Correct option: B.
The presence of hydrogen bonds.
Boric acid is polymeric because of the presence of hydrogen bonds. In the given figure, the dotted lines represent hydrogen bonds.

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MCQ 1431 Mark
$\ce{AlH_3}$​ is an example for:
  • A
    interstitial hydride
  • B
    electron rich hydride
  • C
    ionic hydride
  • ✓
    electron deficient hydride
Answer
Correct option: D.
electron deficient hydride
According to the Bohr's octet rule, each element tends to completely fill its outermost orbit with $8$ electrons in it. Electronic configuration of aluminium is $2, 8, 3$ that means it still needs $5$ more electrons to complete its octet. That's why aluminium is electron deficient.
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MCQ 1441 Mark
Thermodynamically the most stable form of carbon is:
  • A
    Diamond.
  • ✓
    Graphite.
  • C
    Fullerenes.
  • D
    Coal.
Answer
Correct option: B.
Graphite.
Graphite is thermodynamically the most stable form of carbon.
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MCQ 1451 Mark
Quartz is the form ?
  • A
    $ \mathrm{CO}_2$
    ​
  • ✓
    $ \mathrm{SiO}_2$
    ​
  • C
    $\mathrm{SO}_2 $
    ​
  • D
    $ \mathrm{NO}_2 $​
Answer
Correct option: B.
$ \mathrm{SiO}_2$
​
Silica is found in many crystalline and amorphous forms.
Quartz is a crystalline form of silica.
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MCQ 1461 Mark
Silicon has a strong tendency to form polymers like silicones. The chain length of silicone polymer can be controlled by adding.
  • A
    $\mathrm{MeSiCl}_3$.
  • B
    $\mathrm{Me}_2 \mathrm{SiCl}_2$.
  • ✓
    $\mathrm{Me}_3 \mathrm{SiCl}$.
  • D
    $\mathrm{Me}_4 \mathrm{Si}$.
Answer
Correct option: C.
$\mathrm{Me}_3 \mathrm{SiCl}$.
The chain length of the polymer can be controlled by adding $\ce{(CH_3)_3 SiCl}$ which blocks the end as shown below:
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MCQ 1471 Mark
The mixture of $CO$ and $H$, is known as:
  • A
    Producer gas.
  • B
    Synthesis gas.
  • C
    Water gas.
  • ✓
    Both $(b)$ and $(c).$
Answer
Correct option: D.
Both $(b)$ and $(c).$
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MCQ 1481 Mark
The number of possible isomers for disubstituted borazine, $\mathrm{B}_3 \mathrm{N}_3 \mathrm{H}_4 \mathrm{X}_2$​ is:
  • A
    $3$
  • ✓
    $4$
  • C
    $6$
  • D
    $2$
Answer
Correct option: B.
$4$
The number of possible isomers of distributed borazine is $4$ because of $4$ reactive hydrogen ions.
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MCQ 1491 Mark
Aluminium exist in $+3$ state where as thallium exist in both $+1\  \&+3$ oxidation state. Reason for this is
  • ✓
    inert pair effect
  • B
    Lanthanoid contraction
  • C
    Diagonal relationship
  • D
    none of these
Answer
Correct option: A.
inert pair effect
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MCQ 1501 Mark
Which metal powder suspended in oil is used as a paint for mirrors?
  • A
    $Fe$
  • B
    $Sn$
  • C
    $Ag$
  • ✓
    $Al$
Answer
Correct option: D.
$Al$
The reflective property of aluminium is being used here. Powdered aluminium suspended in oil is used as paint. The low cost and easy availability make it useful in this.
This compound is also known as Diaspore having formula $\mathrm{Al}_2 \mathrm{O}_3 \cdot \mathrm{H}_2 \mathrm{O}$.
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MCQ 1511 Mark
The colour of $\mathrm{Co}\left(\mathrm{BO}_2\right)_2$​ is:
  • ✓
    Blue
  • B
    Green
  • C
    Yellow
  • D
    Violet
Answer
Correct option: A.
Blue
When the glassy bead is dipped in $Co$ salt and heated, blue coloured bead is formed.
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MCQ 1521 Mark
Ionisation enthalpy $(\triangle _i \ H_1\  kJ\  mol^{-1})$ for the elements of Group $13$ follows the order.
  • A
    $\text{B > Al > Ga > In > Tl.}$
  • B
    $\text{B < Al < Ga < In < Tl.}$
  • C
    $\text{B < Al > Ga < In > Tl.}$
  • ✓
    $\text{B > Al < Ga > In < Tl.}$
Answer
Correct option: D.
$\text{B > Al < Ga > In < Tl.}$
On moving down the group from $B$ to $TI$, a regular decreasing trend in the ionisation energy values is not observed.
$\ \ \text{B}\ \ \ \ \ \text{Al}\ \ \ \ \ \text{Ga}\ \ \ \ \ \text{In}\ \ \ \ \ \ \text{Tl}\\801\ \ \ 577\ \ \ 579\ \ \ \ 558\ \ \ \ 589\ \ \ \ \ \text{kJ mol}^{-1}$
In Ga, there are ten d-electrons in the penultimate shell which screen the nuclear charge less effectively and thus, outer electron is held firmly. As a result, the ionisation energy of both $Al$ and $Ga$ is nearly the same. The increase in ionisation energy from In to $Tl$ is due to poor screening effect of $14f$ electrons present in the inner shell.
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MCQ 1531 Mark
The second period elements of $p-$ block starting from boron, are restricted to a maximum covalency of :
  • A
    Four $($using $1s, 2s $ and two $2p$ orbitals$).$
  • B
    Six $($using $1s$ and $2s -$ orbitals$)$.
  • ✓
    Four $ ($using $2s$ and three $2p$ orbitals$).$
  • D
    Six $($using $1s$ and three $2p$ orbitals$)$.
Answer
Correct option: C.
Four $ ($using $2s$ and three $2p$ orbitals$).$
The second period elements of $p-$ block starting from boron are restricted to a maximum covalency of four $($using one $2s$ and three $2p$ orbitals$).$
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MCQ 1541 Mark
The platinum wire which is used in borax bead test is dipped in:
  • ✓
    powdered borax
  • B
    metaboric acid
  • C
    orthoboric acid
  • D
    all
Answer
Correct option: A.
powdered borax
The borax bead test is the most common. A small loop is formed at the end of a platinum wire. The loop is cleaned with concentrated hydrochloric acid and dipped in powdered borax, then heated in the flame of a Bunsen burner until the borax melts, forming a bead.
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MCQ 1551 Mark
The aqueous solution of borax turns red litmus to :
  • A
    Blue
  • ✓
    No Change
  • C
    Red
  • D
    White
Answer
Correct option: B.
No Change
This is because of the alkanline nature of the aqueous solution of borax.
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MCQ 1561 Mark
The increasing order of atomic radius:
  • A
    $\text{Al < Ga < In < TI.}$
  • ✓
    $\text{Ga < Al < In < TI.}$
  • C
    $\text{Al < In < Ga < TI.}$
  • D
    $\text{Al < Ga < TI < In.}$
Answer
Correct option: B.
$\text{Ga < Al < In < TI.}$
$Ga$ is smaller than $'Al\ '$ due to poor shelling effect of $d-$electron effective nuclear charge increases.
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MCQ 1571 Mark
Which of the following is solid at room temperature?
  • A
    $\text{CO}$
  • B
    $ \mathrm{CO}_2 $
  • ✓
    $ \mathrm{SiO}_2 $
  • D
    $\mathrm{OF}_2 $
Answer
Correct option: C.
$ \mathrm{SiO}_2 $
Silicon dioxide involves covalent $\text{Si−O}$ bonds. It has strong van der waal's forces of interactions and thus exists as solids.
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MCQ 1581 Mark
The property which does not support anomalous behaviour of boron is :
  • ✓
    Formation of trihalides.
  • B
    High ionisation energy.
  • C
    Small size.
  • D
    High electronegativity.
Answer
Correct option: A.
Formation of trihalides.
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MCQ 1591 Mark
Graphite cleaves easily between the layers. Thus, it is :
  • A
    Soft.
  • B
    Slippery.
  • ✓
    Both $(a)$ and $(b).$
  • D
    None of these.
Answer
Correct option: C.
Both $(a)$ and $(b).$
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MCQ 1601 Mark
The colour of blue glass is due to the presence of oxide of :
  • A
    Chromium
  • ✓
    Cobalt
  • C
    Gold
  • D
    Silver
Answer
Correct option: B.
Cobalt
Cobalt is a very intense glass colorant and very little is required to show a noticeable amount of colour. Colour of Cobalt glass is blue.
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MCQ 1611 Mark
Borax is known as :
  • A
    Sodium borate.
  • B
    Sodium tetra borate.
  • C
    isodium tetra borate.
  • ✓
    All
Answer
Correct option: D.
All
Borax : $\mathrm{Na}_2\left[\mathrm{~B}_4 \mathrm{O}_5(\mathrm{OH})_4\right] \cdot 8 \mathrm{H}_2 \mathrm{O}$.
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MCQ 1621 Mark
Group $13$ elements are attacked by non$-$oxidising acids except:
  • A
    Aluminium
  • B
    Gallium
  • C
    Indium
  • ✓
    Boron
Answer
Correct option: D.
Boron
Boron is not attacked by non-oxidising acids such as $\text{HCl}$ but reacts with oxidising acids such as conc. $\mathrm{HNO}_3$ and conc. $\mathrm{H}_2 \mathrm{SO}_4$​ forming boric acid.
Boron, being chemically a non$-$metal, is resistant to attack by non$-$oxidising acids but the other members of the group react with non$-$oxidising acids as typical metals and evolve hydrogen.
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MCQ 1631 Mark
Aluminium is much more reactive than iron because its standard reduction potential is higher than iron. Still, aluminium is less easily corroded than iron because :
  • A
    Aluminium reacts with atmospheric carbon dioxide to form a self$-$protective layer of $\ce{Al_2​O_3}$​.
  • ✓
    It has a higher reducing power and forms a self protective layer of $\ce{Al_2​O_3}$​​.
  • C
    it has a higher reducing power and does not react with oxygen so easily.
  • D
    both $A$ and $B.$
Answer
Correct option: B.
It has a higher reducing power and forms a self protective layer of $\ce{Al_2​O_3}$​​.
Aluminium is much more reactive than iron because its standard reduction potential is higher than iron. However, aluminium is still less easily corroded than iron because oxygen forms a protective oxide layer of $\ce{Al_2​O_3}$​​ on its surfac.
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MCQ 1641 Mark
Which of the following strongest lewis acid :
  • A
    $\mathrm{BCl}_3$
  • B
    $\mathrm{BF}_3$
  • ✓
    $\mathrm{BI}_3$
  • D
    $\mathrm{BBr}_3$
Answer
Correct option: C.
$\mathrm{BI}_3$
$\mathrm{BI}_3$ because backbonding is least effective between $5p-5p$ overlapping.
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