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Chemistry M.C.Q (1 Marks)

The p-Block Elements · CBSE STD 12 Science (CBSE - English Medium). 153 questions.

Questions · Page 3 of 4

M.C.Q (1 Marks)

MCQ 1011 Mark
Most abundant uncombined element present in atmosphere is:
  • A
    $Ca$
  • B
    $Mg$
  • C
    $Al$
  • ✓
    $N$
Answer
Correct option: D.
$N$
Nitrogen gas $N_2$​ makes up about $78\%$ of the atmosphere by volume.
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MCQ 1021 Mark
A degenerate gas is:
  • A
    $He$
  • B
    $O_2$
  • ✓
    $\text{He(ll)}$
  • D
    $He_2$
Answer
Correct option: C.
$\text{He(ll)}$
$\text{He(II)}$ is a degenerate gas. A degenerate gas is one where quantum mechanical effects on the electrons dominate the behavior.A degenerate electron gas can permanently withstand the self$-$gravitation. its energy cannot be radiated away.
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MCQ 1031 Mark
How is ammonia collected?
  • ✓
    Ammonia is less dense than air so it is collected by upward delivery.
  • B
    Ammonia is more dense than air so it is collected by upward delivery.
  • C
    Ammonia is more dense than air so it is collected by downward delivery.
  • D
    None of the above.
Answer
Correct option: A.
Ammonia is less dense than air so it is collected by upward delivery.
Ammonia is less dense than air so it is collected by upward delivery or gas syringe method.
In upward delivery method a gas jar is connected by a tube to flask that is giving off gas.
The gas that is less dense than air rises to the top of gas jar.
The air in the gas jar is displaced until the gas jar is filled with collected gas.
Ammonia is very soluble gas so the collection apparatus should be dry and not collected over water.
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MCQ 1041 Mark
Among $VA$ group elements, the element which has highest ionization energy?
  • ✓
    $N$
  • B
    $P$
  • C
    $Sb$
  • D
    $Bi$
Answer
Correct option: A.
$N$
Among $VA$ group elements, the element which has highest ionization energy is nitrogen.
The ionization energy of $VA$ group elements decreases on moving down the group $($from $N$ to $Bi),$ due to gradual increase in atomic size.
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MCQ 1051 Mark
All noble gases are:
  • A
    Colourlful.
  • ✓
    Colourless and odourless.
  • C
    Colourless and but have odour.
  • D
    None of these.
Answer
Correct option: B.
Colourless and odourless.
All the noble gases are colourless and odourless gases, in addition to being chemically inert and stable.
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MCQ 1061 Mark
On addition of conc. $\mathrm{H}_2 \mathrm{SO}_4$ to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because
  • A
    $\mathrm{H}_2 \mathrm{SO}_4$ reduces $HI$ to $I_2$.
  • B
    $HI$ is of violet colour.
  • ✓
    $HI$ gets oxidised to $I_2$.
  • D
    $HI$ changes to $\ce{HIO_3}$.
Answer
Correct option: C.
$HI$ gets oxidised to $I_2$.
$HI$ formed during reaction is oxidized to $I_2$ which is violet in colour.
$2\text{NaCl}+\text{H}_2\text{SO}_4\rightarrow\text{Na}_2\text{SO}_4+2\text{HCl}$
In case of iodine, the halogen acid obtained $(HI)$ is oxidized to free iodine.
$2\text{NaI}+\text{H}_2\text{SO}_4\rightarrow\text{Na}_2\text{SO}_4+2\text{HI}\ \xrightarrow{{\text{H}_2\text{SO}_4}\ \ }\ 2\text{H}_2\text{O}+\text{SO}_2+\text{I}_2$
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MCQ 1071 Mark
The reaction of $Xe$ with an excess of $F-2$​ at high pressure and $573K$ yields:
  • A
    $\ce{XeF_2}$
  • B
    $\ce{XeF_4}$
  • ✓
    $\ce{XeF_6}$
  • D
    $\ce{XeF_3}$
Answer
Correct option: C.
$\ce{XeF_6}$
The reaction of $Xe$ with on excess of $F_2$ at high pressure leads to the formation of $\ce{XeF_6}$
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MCQ 1081 Mark
Which of the following is not tetrahedral in shape?
  • A
    $\text{NH}_4^+$
  • B
    $\text{SiCl}_4$
  • ✓
    $\text{SF}_4$
  • D
    $\ce{SO_4}^{2-}$
Answer
Correct option: C.
$\text{SF}_4$

It has trigonal bipyramidal geometry having $\ce{sp^3d}$ hydridisation.
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MCQ 1091 Mark
Which reaction of ammonia forms the first step of Ostwald's process?
  • ✓
    The catalytic oxidation of ammonia by platinum catalyst.
  • B
    The catalytic oxidation of ammonia by cobalt catalyst.
  • C
    The catalytic reduction of ammonia by platinum catalyst.
  • D
    The oxidation of ammonia.
Answer
Correct option: A.
The catalytic oxidation of ammonia by platinum catalyst.
The first step of Ostwald's process is the catalytic oxidation of ammonia by platinum catalyst for the formation of nitric acid.
$\text{NH}_3\text{O}_2\xrightarrow{\text{Pt}}\text{NO}+\text{H}_2\text{O}$
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MCQ 1101 Mark
The heat of vaporization is very high for ?
  • A
    $He$
  • B
    $Ne$
  • C
    $Ar$
  • ✓
    $Xe$
Answer
Correct option: D.
$Xe$
Heat of vapourisation $\times $ van der Waal's forces $\times $ malecular mass $Xe$ has high malecular mass Therefore heat of vapourisation is very high for $Xe$
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MCQ 1111 Mark
Which of the following belongs to the halogen family?
  • A
    Francium
  • B
    Polonium
  • C
    Radium
  • ✓
    Astatine
Answer
Correct option: D.
Astatine
Astatine belongs to halogen family.
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MCQ 1121 Mark
The oxidation state of chlorine in bleaching powder is:
  • A
    $-2$
  • B
    $-1$
  • C
    $+1$
  • ✓
    $-1$ and $+1$
Answer
Correct option: D.
$-1$ and $+1$
The chemical formula of bleaching powder is $\ce{CaOCl_2}$.
Here, calcium is bonded to $Cl^-$ ion and $\text{OCl}^-$ ion respectively.
In $Cl−$ the oxidation state of chlorine is $-1$ and in $\text{OCl}^-$ ion the oxidation state of chlorine is $+1.a\ 21$
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MCQ 1131 Mark
Which of the following elements can be involved in $\text{p}\pi-\text{d}\pi$ bonding?
  • A
    Carbon.
  • B
    Nitrogen.
  • ✓
    Phosphorus.
  • D
    Boron.
Answer
Correct option: C.
Phosphorus.
Phosphorus can be involved in $\text{p}\pi-\text{d}\pi$ bonding due to presence of vacant $d$ orbitals $C, N,$ and $B$ do not have $o\ ’$ orbitals.
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MCQ 1141 Mark
Which of the following halogens does not form oxyacids at room temperature?
  • ✓
    $F_2$​
  • B
    $Cl_2$​
  • C
    $Br_2$​
  • D
    $I_2$
Answer
Correct option: A.
$F_2$​
Fluorine does not hove $d-$sub shell so it can only have one oxidation state.
Therefore, it cann't form oxy acids. Fluorine is the most electronegative element and always show $−1$ oxiadation state. In oxyacids. reast of the halogens have positive oxidation state.
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MCQ 1151 Mark
Essential constituents of plants and animal tissues are:
  • ✓
    $N$ and $P$
  • B
    $N$ and $As$
  • C
    $Cu$ and $Mg$
  • D
    $Ca$ and $Mg$
Answer
Correct option: A.
$N$ and $P$
Nitrogen $(N),$ phosphorus $(P)$ and potassium $(K)$ are present in plant tissue in quantities from $0.2\%$ to $4.0\%\ ($on a dry matter weight basis$).$
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MCQ 1161 Mark
In $P_4\ ($tetrahedral$):$
  • A
    Each $P$ is joined to four $P.$
  • ✓
    Each $P$ is joined to three $P.$
  • C
    Each $P$ is joined to two $P.$
  • D
    $P_4$​ does not exist.
Answer
Correct option: B.
Each $P$ is joined to three $P.$
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MCQ 1171 Mark
If chlorine gas is passed through hot $\text{NaOH}$ solution, two changes are observed in the oxidation number of chlorine during the reaction. These are $......$ and $......$
$A. 0$ to $+5$
$B. 0$ to $+3$
$C. 0$ to $–1$
$D. 0$ to $+1$
  • A
    $A$ and $B$
  • ✓
    $A$ and $c$
  • C
    $b$ and $c$
  • D
    $A$ and $d$
Answer
Correct option: B.
$A$ and $c$
$6\text{NaOH}+3\text{Cl}_2\xrightarrow{\ \ \ \ \ \ \ \ }5\text{NaCl}+\text{NaClO}_3+3\text{H}_2\text{O}$
When chlorine gas is passed through hot $\text{NaOH}$ solution it produces $\text{NaCl}$ and $\mathrm{NaClO}_3$. Thus oxidation state of chlorine changes from $0$ to $-1$ and $0$ to $+5$ respectively.
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MCQ 1181 Mark
One mole of magnesium nitride on the reaction with an excess of water gives:
  • A
    One mole of ammonia.
  • B
    One mole of nitric acid.
  • ✓
    Two moles of ammonia.
  • D
    Two moles of nitric acid.
Answer
Correct option: C.
Two moles of ammonia.
Hint: Nitride on reaction with water gives ammonia
Step $1:\ $ Formula of magnesium nitride
The formula for magnesium nitride will be $\ce{Mg_3​N_2}​$
Step $2:\ $ Recation of magnesium nitrid
$\mathrm{Mg}_3 \mathrm{~N}_2+6 \mathrm{H}_2 \mathrm{O} \rightarrow 3 \mathrm{Mg}(\mathrm{OH})_2+2 \mathrm{NH}_3$
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MCQ 1191 Mark
Among the following the correct statement is:
  • A
    Phosphates have no biological significance in humans.
  • B
    Between nitrates and phosphates, phosphates are less abundant in earth's crust.
  • ✓
    Between nitrates and phosphates, nitrates are less abundant in earth's crust.
  • D
    Oxidation of nitrates is possible in soil.
Answer
Correct option: C.
Between nitrates and phosphates, nitrates are less abundant in earth's crust.
Nitrates are less abundant than phosphates in the earth's crust because they are soluble in water. Moreover they can also be reduced by numerous microbes present in earth's crust.
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MCQ 1201 Mark
Which of the following acids forms three series of salts?
  • A
    $ \mathrm{H}_3 \mathrm{PO}_2 $
  • B
    $ \mathrm{H}_3 \mathrm{BO}_3 $
  • ✓
    $ \mathrm{H}_3 \mathrm{PO}_4 $
  • D
    $ \mathrm{H}_3 \mathrm{PO}_3 $
Answer
Correct option: C.
$ \mathrm{H}_3 \mathrm{PO}_4 $
Structure of $ \mathrm{H}_3 \mathrm{PO}_4 $ is

$ \mathrm{H}_3 \mathrm{PO}_4 $​​​​​​​ has $3-OH$ groups i.e., has three ionisable $H-$atoms and hence forms three series of salts. These three possible series of salts of $ \mathrm{H}_3 \mathrm{PO}_4 $ are as follows:
$\mathrm{NaH}_2 \mathrm{PO}_4, \mathrm{NaHPO}_4$ and $\mathrm{Na}_3 \mathrm{PO}_4$
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MCQ 1211 Mark
The element that oxidizes water to $\mathrm {O_2}$ with a large evolution of heat is:
  • ✓
    $ \mathrm{F}_2 $
  • B
    $ \mathrm{Cl}_2 $
  • C
    $ \mathrm{Br}_2 $
  • D
    $ \mathrm{I}_2 $
Answer
Correct option: A.
$ \mathrm{F}_2 $
$ \mathrm{F}_2 $ is the most powerful oxidizing agent and evolves large amount of heat due to the formation of $H -$ bond with $ \mathrm{H_2O} ($It is also the most electronegative element$)$
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MCQ 1221 Mark
Total number of covalent bonds in a white phosphorous molecule is:
  • A
    $1$
  • B
    $4$
  • C
    $3$
  • ✓
    $6$
Answer
Correct option: D.
$6$
Number covalent bonds present in white phosphorous $P_4$​ is $6.$
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MCQ 1231 Mark
In a cyclotrimetaphosphoric acid molecule, how many single and double bonds are present?
  • A
    $3$ double bonds$; 9$ single bonds.
  • B
    $6$ double bonds$; 6$ single bonds.
  • ✓
    $3$ double bonds$; 12$ single bonds.
  • D
    Zero double bonds$; 12$ single bonds.
Answer
Correct option: C.
$3$ double bonds$; 12$ single bonds.
Structure of Cyclotrimetaphosphoric acid.
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MCQ 1241 Mark
In solid state $\ce{PCl_5}$ is a _________.
  • A
    Covalent solid.
  • B
    Octahedral structure.
  • C
    Ionic solid with $\ce{[PCl_6]^+}$ octahedral and $\ce{[PCl_4]^-}$ tetrahedra.
  • ✓
    Ionic solid with $\ce{[PCl_4]^+}$ tetrahedral and $\ce{[PCl_6]^-}$ octahedra.
Answer
Correct option: D.
Ionic solid with $\ce{[PCl_4]^+}$ tetrahedral and $\ce{[PCl_6]^-}$ octahedra.
Structure of $\ce{PCl_5}$ in solid state.
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MCQ 1251 Mark
Elements of group $-15$ form compounds in $+5$ oxidation state. However, bismuth forms only one well characterised compound in $+5$ oxidation state. The compound is
  • A
    $\ce{Bi_2O_5}$
  • ✓
    $\ce{BiF_5}$
  • C
    $\ce{BiCl_5}$
  • D
    $\ce{Bi_2S_5}$
Answer
Correct option: B.
$\ce{BiF_5}$
Stability of $+5$ state decreases from top to bottom but because of high electronegativity and smaller size of fluorine bismuth can exist in this form.
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MCQ 1261 Mark
The characteristic of the last elements in the periods of a periodic table:
  • A
    Orbital completely.
  • B
    Zero electron affinity.
  • C
    Zero tendency in accepting electrons.
  • ✓
    All of these.
Answer
Correct option: D.
All of these.
In a period the last element will have completely filled configuration by filling up that orbital completely. Hence they are called noble gases or inert elements as they do not participate in the bonding formation. They are also called zero group elements as they have zero electron affinity that is zero tendency in accepting electrons as they already have stability.
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MCQ 1271 Mark
The electronic configuration of halogens in their valence shell is:
  • A
    $\mathrm{ns}^2$
  • B
    $\ce{ns^2 np^6}$
  • C
    $ns^0$
  • ✓
    $\ce{ns^2 np^5}$
Answer
Correct option: D.
$\ce{ns^2 np^5}$
Electronic configuration of halogens in their valence shells $\ce{= ns^2 np^5}$
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MCQ 1281 Mark
Strong reducing behaviour of $\mathrm{H}_3 \mathrm{PO}_2$ is due to
  • A
    Low oxidation state of phosphorus.
  • B
    Presence of two$-OH$ groups and one $P-H$ bond.
  • ✓
    Presence of one$-OH$ group and two $P-H$ bonds.
  • D
    High electron gain enthalpy of phosphorus.
Answer
Correct option: C.
Presence of one$-OH$ group and two $P-H$ bonds.
In $\mathrm{H}_3 \mathrm{PO}_2,$ two H atoms are bonded directly to $P$ atom which imparts reducing character to the acid.
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MCQ 1291 Mark
Calcium cyanamide on treatment with steam produces:
  • A
    $\mathrm{NH}_3+\mathrm{CaO}$
  • B
    $\mathrm{NH}_3+\mathrm{CaHCO}$
  • ✓
    $\mathrm{NH}_3+\mathrm{CaCO}_3$
  • D
    $\mathrm{NH}_3+\mathrm{Ca}(\mathrm{OH})_2$
Answer
Correct option: C.
$\mathrm{NH}_3+\mathrm{CaCO}_3$
Reaction:
$\mathrm{CaCN}_2+3 \mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{CaCO}_3+\mathrm{NH}_3$
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MCQ 1301 Mark
The halogen which can form both cations and anions is:
  • A
    $F$
  • B
    $Cl$
  • C
    $Br$
  • ✓
    $I$
Answer
Correct option: D.
$I$
Iodine can form both cations, as well as anions. Iodine can form cations due to the poor shielding effect of $d$ orbitals where electrons can be removed from the valence shell and the cation is formed. The cations and anions of Iodine is represented as follow:
$I^{-}$and $I^{+}$
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MCQ 1311 Mark
Which of the following is correct for $P_4$ molecule of white phosphorus?
It has $6$ lone pairs of electrons.
It has six $P–P$ single bonds.
It has three $P–P$ single bonds.
It has four lone pairs of electrons.
  • A
    $a$ and $b$
  • B
    $a$ and $c$
  • C
    $b$ and $c$
  • ✓
    $b$ and $d$
Answer
Correct option: D.
$b$ and $d$

It has four lone pairs of electrons at each $p-$atom.
It has six $p-p$ single bond.
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MCQ 1321 Mark
Hydride of nitrogen is called:
  • A
    Hydrogen sulphide.
  • B
    Water.
  • ✓
    Ammonia.
  • D
    Nitrous oxide.
Answer
Correct option: C.
Ammonia.
Hydride of nitrogen is the binary compound formed by the combination of hydrogen and nitrogen.
The hydride formed with nitrogen is ammonia $(\ce{NH_3}).$
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MCQ 1331 Mark
The word Argon means $.......$
  • A
    Noble
  • B
    Now
  • C
    Strange
  • ✓
    Lazy
Answer
Correct option: D.
Lazy
The name "argon" is derived from the Greek word , meaning "lazy" or "inactive", as a reference to the fact that the element undergoes almost no chemical reactions.
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MCQ 1341 Mark
In Haber's process for the manufacture of ammonia, the catalyst used is:
  • A
    Finely divided nickel.
  • B
    Finely divided molybdenum.
  • ✓
    Finely divided iron.
  • D
    Finely divided platinum.
Answer
Correct option: C.
Finely divided iron.
Finely divided iron is used as catalyst in the manufacture of ammonia by Haber's process.
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MCQ 1351 Mark
Nitrogen differs from $\text{P, As, Sb}$ and $Bi$ in the following properties:
  • A
    It forms diatomic molecule.
  • B
    It is not able to extent its coordination number beyond four.
  • C
    Nitrogen does not function as a Lewis acid whereas $\text{P, As, Sb}$ and $Bi$ do so.
  • ✓
    In all the properties given above.
Answer
Correct option: D.
In all the properties given above.
As vacant $d-$orbital are present in $P$ and other elements of this group except $N$ so they can expand their valency and forms stable pentavalence product but due to absence of $d-$orbitals nitrogen cannot form pentavalence products. It forms diatomic molecule $N_2$
Nitrogen does not function as a Lewis acid due to absence of $d-$orbitals and it is a Lewis base due to presence of lone pair.
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MCQ 1361 Mark
Which of the following non$-$metals belongs to the halogen family?
  • A
    Flourine
  • B
    Chlorine
  • C
    Bromine
  • ✓
    All of the above
Answer
Correct option: D.
All of the above
Elements of $17^{th}$ group are called halogens. It contains fluorine$(F),$ Chlorine$(Cl),$ Bromine$(Br),$ Iodine$(I)$ and Astatine$(At).$
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MCQ 1371 Mark
Which of the following pairs of ions are isoelectronic and isostructural?
  • ✓
    $\text{CO}_3^{2-},\text{NO}_3^-$
  • B
    $\text{ClO}_3^-,\text{CO}_3^{2-}$
  • C
    $\text{SO}_3^{2-},\text{NO}_3^-$
  • D
    $\text{ClO}_3^-,\text{SO}_3^{2-}$
Answer
Correct option: A.
$\text{CO}_3^{2-},\text{NO}_3^-$
No. of electron in both the molecule is $= 32,$
Both has similar structure that is triangular planar.
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MCQ 1381 Mark
Which of the following statements are correct?
$a. S-S$ bond is present in $\mathrm{H}_2 \mathrm{S}_2 \mathrm{O}_6$.
$b.$ In peroxosulphuric acid $\left(\mathrm{H}_2 \mathrm{SO}_5\right)$ sulphur is in $+6$ oxidation state.
$c.$ Iron powder along with $\mathrm{Al}_2 \mathrm{O}_3$ and $\mathrm{K}_2 \mathrm{O}$ is used as a catalyst in the preparation of $\mathrm{NH}_3$ by Haber's process.
$d.$ Change in enthalpy is positive for the preparation of $\mathrm{SO}_3$ by catalytic oxidation of $\mathrm{SO}_2$.
  • ✓
    $a$ and $b$
  • B
    $a$ and $c$
  • C
    $b$ and $c$
  • D
    $a$ and $d$
Answer
Correct option: A.
$a$ and $b$

In $\mathrm{H}_2 \mathrm{SO}_5$, there is a peroxo$-$linkage.

$(O$ in peroxide linkage has oxidation state$-1)$
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MCQ 1391 Mark
An element with variable $($more than one$)$ valency stored under water is:
  • A
    Silicon.
  • B
    Iron.
  • ✓
    Phosphorus.
  • D
    Gold.
Answer
Correct option: C.
Phosphorus.
Phosphorous can accept either $3$ electrons or donate $5$ electrons depending on the neighborhood element. Hence, it has variable valency. The allotropic form of phosphorus $($white phosphorus$)$ is less stable and therefore highly reactive because of angular strain in $P_4$​ molecule where the angles are only $60^\circ .$
It readily catches fire in air to give dense white fumes of $\ce{P_4O_{10}}$. Therefore, it is kept in water to avoid oxidation by the oxygen present in the air. It is kept in water because it is insoluble in water.
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MCQ 1401 Mark
Which of the following statements is not correct?
  • A
    All halogens except flourine from $\text{OXO}-$acids.
  • B
    Hypohalous acids $\text{HOCI, HOBr}$ and $\text{HOI}$ are all strong acids.
  • C
    Hypochlorous acid is the most stable among hypohalous acids.
  • ✓
    Chlorous acid is the only halous acid known.
Answer
Correct option: D.
Chlorous acid is the only halous acid known.
There are also other halous acids like:
$\mathrm{HOBr}_2$ which is Hydrobromous acid.
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MCQ 1411 Mark
The lightest gas which is non$-$inflammable is:
  • A
    $H_2$
  • ✓
    $He$
  • C
    $N_2$
  • D
    $Ar$
Answer
Correct option: B.
$He$
$H_2$​ is the lightest gas but it is inflammable.
$He$ is the next lightest gas and it is non$-$inflammable.
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MCQ 1421 Mark
Warming ammonium sulphate with sodium hydroxide solution gives:
  • ✓
    Ammonia.
  • B
    Chlorine.
  • C
    Nitrogen.
  • D
    None of these.
Answer
Correct option: A.
Ammonia.
$\left(\mathrm{NH}_4\right) 2 \mathrm{SO}_4+2 \mathrm{NaOH} \rightarrow \mathrm{Na}_2 \mathrm{SO}_4+2 \mathrm{H}_2 \mathrm{O}+2 \mathrm{NH}_3$
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MCQ 1431 Mark
Zero group elements are known as $.......$
  • A
    Alkali metals.
  • B
    Alkaline earth metals.
  • C
    Transition metals.
  • ✓
    Inert gases.
Answer
Correct option: D.
Inert gases.
The elements of group $0$ have stable complete octate configuration. As a result, they do not react with other elements easily, i.e., they have inert behavior.
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MCQ 1441 Mark
A brown ring is formed in the ring test for $\text{NO}_3^-$ ion. It is due to the formation of
  • ✓
    $[\text{Fe}(\text{H}_2\text{O})_5(\text{NO})]^{2+}$
  • B
    $\text{FeSO}_4.\text{NO}_2$
  • C
    $[\text{Fe}(\text{H}_2\text{O})_4(\text{NO})_2]^{2+}$
  • D
    $\text{FeSO}_4.\text{HNO}_3$
Answer
Correct option: A.
$[\text{Fe}(\text{H}_2\text{O})_5(\text{NO})]^{2+}$
When freshly prepared solution of $\mathrm{FeSO}_4$ is added in a solution containing $\mathrm{NO}_3$ ion, it leads to formation of a brown coloured complex. This is known as brown ring test of nitrate.
$\text{NO}_3^-+3\text{Fe}^{2+}+4\text{H}^+\xrightarrow{\ \ \ \ \ \ \ \ \ \ }\ \text{NO}+3\text{Fe}^{3+}+2\text{H}_2\text{O}$
$[\text{Fe}(\text{H}_2\text{O})_6]^{2+}+\text{NO}\xrightarrow{\ \ \ \ \ \ \ \ \ \ }[\text{Fe}(\text{H}_2\text{O})_5(\text{NO})]^{2+}+\text{H}_2\text{O}\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ^{\text{Brown ring}}$
Hence, 2 moles of ammonia will produce $2$ moles of $NO.$
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MCQ 1451 Mark
Urea is prepared by the chemical reaction of:
  • A
    Acetamide and ethyl alcochol.
  • B
    Ammonium sulphate and calcium chloride.
  • ✓
    Ammonia and Carbon dioxide.
  • D
    Chlorine and water.
Answer
Correct option: C.
Ammonia and Carbon dioxide.
The chemical formula of urea is $\mathrm{H}_2 \mathrm{N}-\mathrm{CO}-\mathrm{NH}_2$
Urea is now prepared commercially in vast amounts from liquid ammonia and liquid carbon dioxide.
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MCQ 1461 Mark
In qualitative analysis when $\ce{H_2S}$ is passed through an aqueous solution of salt acidified with dil$. \text{HCl},$ a black precipitate is obtained. On boiling the precipitate with dil$. \ce{HNO_3},$ it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution gives $......$
  • A
    Deep blue precipitate of $\mathrm{Cu}(\mathrm{OH})_2$.
  • ✓
    Deep blue solution of $\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}$.
  • C
    Deep blue solution of $\mathrm{Cu}\left(\mathrm{NO}_3\right)_2$.
  • D
    Deep blue solution of $\mathrm{Cu}(\mathrm{OH})_2 \cdot \mathrm{Cu}\left(\mathrm{NO}_3\right)_2$.
Answer
Correct option: B.
Deep blue solution of $\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}$.
Black precipitate of copper sulphide is formed which gives blue colour of copper nitrate on boiling with dilute $\ce{HNO_3}.$ When aqueous solution of ammonia is added to it, deep blue colour of
$\text{Cu}^{2+}+\text{H}_2\text{S}\ \xrightarrow{\ \ \ \ \ \ \ \ \ }\ \text{CuS}+2\text{H}^+,\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Black}$
$\text{CuS}+\text{dil. }\text{HNO}_3\ \xrightarrow{\ \ \ \ \ \ \ \ \ \ }\ \text{Cu}(\text{NO}_3)_2\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Blue}$
$\text{Cu}(\text{NO}_3)_2+4\text{NH}_3\xrightarrow{\ \ \ \ \ \ \ \ \ \ }[\text{Cu}(\text{NH}_3)_4]^{2+}\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Deep blue}$
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MCQ 1471 Mark
Which is the lightest gas?
  • A
    Helium
  • B
    Oxygen
  • ✓
    Hydrogen
  • D
    Nitrogen
Answer
Correct option: C.
Hydrogen
Atomic weight of hydrogen is least so it is the lightest gas.
Hydrogen dirigibles are able to float in the atmosphere.
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MCQ 1481 Mark
Ammonia is not a product in the:
  • A
    Hydrolysis of nitrolim.
  • B
    Hydrolysis of aluminium nitride.
  • ✓
    Decomposition of ammonium nitrite.
  • D
    Hydrolysis of urea.
Answer
Correct option: C.
Decomposition of ammonium nitrite.
$\mathrm{NH}_3 \mathrm{NO}_3 \rightarrow \mathrm{N}_2 \mathrm{O}+2 \mathrm{H}_2 \mathrm{O}$
Nitrous oxide is produced after decomposition of ammonium nitrite instead of ammonia.
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MCQ 1491 Mark
Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidising power.
Ion $\text{ClO}_4^-$ $\text{IO}_4^-$ $\text{BrO}_4^-$
Reduction potential $\text{E}^{\ominus}/\text{V}$ $\text{E}^{\ominus}=1.19\text{V}$ $\text{E}^{\ominus}=1.65\text{V}$ $\text{E}^{\ominus}=1.74\text{V}$
  • A
    $\text{ClO}_4^->\text{IO}_4^->\text{BrO}_4^-$
  • B
    $\text{IO}_4^->\text{BrO}_4^->\text{ClO}_4^-$
  • ✓
    $\text{BrO}_4^->\text{IO}_4^->\text{ClO}_4^-$
  • D
    $\text{BrO}_4^->\text{ClO}_4^->\text{IO}_4^-$
Answer
Correct option: C.
$\text{BrO}_4^->\text{IO}_4^->\text{ClO}_4^-$
Higher the standard reduction potential higher will be the oxidizing power.
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MCQ 1501 Mark
Which of the following orders are correct as per the properties mentioned against each?
$a.$ $\ce{As_2O_3 < SiO_2 < P_2O_3 < SO_2}$ Acid strength.
$b.$ $\ce{AsH_3 < PH_3 < NH_3}$ Enthalpy of vapourisation.
$c.$ $\ce{S < O < Cl < F}$ More negative electron gain enthalpy.
$d.$ $\ce{H_2O > H_2S > H_2Se > H_2Te}$ Thermal stability.
  • A
    $a$ and $b$
  • B
    $b$ and $c$
  • C
    $a$ and $c$
  • ✓
    $a$ and $d$
Answer
Correct option: D.
$a$ and $d$
  1. $\ce{As_2O_3 < SiO_2 < P_2O_3 < SO_2}$ Order of acid strength.
  2. Correct order of enthalpy of vaporization is $\ce{AsH_3 > PH_3 > NH_3}$
  3. Correct order of more negative electron gain enthalpy $\ce{S < O < FH_2Se > H_2Te}$
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M.C.Q (1 Marks) - Page 3 - Chemistry STD 12 Science Questions - Vidyadip