Question 11 Mark
Write balanced equations for:
$\mathrm{B}_2 \mathrm{H}_6+\mathrm{NH}_3 \rightarrow$
Answer$3\text{B}_6\text{H}_6+6\text{NH}_3\rightarrow 3\big[\text{BH}_2(\text{NH}_3)_2\big]^{+}\big[\text{BH}_4\big]^{-}\rightarrow 2\text{B}_3\text{N}_3\text{H}_6+12\text{H}_2 \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Borazene}$
View full question & answer→MCQ 21 Mark
The type of hybridisation of boron in diborane is:
- A
$sp$.
- B
$\mathrm{sp}^2$.
- ✓
$\mathrm{sp}^3$.
- D
$\mathrm{dsp}^2$.
AnswerCorrect option: C. $\mathrm{sp}^3$.
Boron in diborane is $\mathrm{sp}^3$ hybridized.
View full question & answer→Question 31 Mark
Give reasons:
Aluminium wire is used to make transmission cables.
AnswerAluminium is generally unaffected by air and moisture and it is also good conductor of electricity. That’s why it is used in transmission cables.
View full question & answer→MCQ 41 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.
AnswerCorrect 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.
View full question & answer→MCQ 51 Mark
An aqueous solution of borax is :
AnswerBorax is a salt of a strong base $(\mathrm{NaOH})$ and a weak acid $\left(\mathrm{H}_3 \mathrm{BO}_3\right)$. It is, therefore, basic in nature.
View full question & answer→Question 61 Mark
Write balanced equations for:
$\mathrm{B}_2 \mathrm{H}_6+\mathrm{H}_2 \mathrm{O} \rightarrow$
Answer$\ \ \text{B}_2\text{H}_6 \ \ \ \ + \ \ \ \ 6\text{H}_2\text{O} \ \ \ \ \ \ \ \ \rightarrow \ \ \ \ \ \ \ \ \ 2\text{H}_3\text{BO}_3 \ \ \ \ + \ \ \ \ \ 6\text{H}_2 \\ \text{Diborane} \ \ \ \ \ \text{Water} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Orthoboric acid} \ \ \ \ \ \text{Hydrogen}$
View full question & answer→Question 71 Mark
Write balanced equations for:
$\mathrm{NaH}+\mathrm{B}_2 \mathrm{H}_6 \rightarrow$
Answer$\ \ \ \ \ \text{B}_2\text{H}_6 \ \ \ \ \ + \ \ \ \ \ 2\text{NaH} \ \ \ \ \ \ \xrightarrow{\text{ether}} \ \ \ \ \ 2\text{HaBH}_4 \\ \text{Diborane} \ \ \ \ \ \ \text{Sodium hydride } \ \ \ \ \ \ \ \text{Sodium borohydride}$
View full question & answer→Question 81 Mark
Give reasons:
Diamond is used as an abrasive.
AnswerDiamond is used as an-abrasive because it is an extremely hard substance.
View full question & answer→Question 91 Mark
Write balanced equations for:
$\mathrm{BF}_3+\mathrm{LiH} \rightarrow$
Answer$\ \ \ \ \ \ \ \ \ \ \ \ \ \ 2\text{BF}_3 \ \ \ \ \ + \ \ \ \ \ 6\text{LiH} \ \ \ \ \ \ \ \ \ \rightarrow \ \ \ \ \ \ \ \ \ \text{B}_2\text{H}_6 \ \ \ \ \ + \ \ \ \ \ 6\text{LiF} \\ \ \ \text{Boron trifluride} \ \ \ \text{Lithium hydride} \ \ \ \ \ \ \ \text{Diiborane} \ \ \ \text{Lithium fluoride}$
View full question & answer→Question 101 Mark
Write balanced equations for:
$\text{H}_3\text{BO}_3\xrightarrow{\Delta}$
Answer$4\text{H}_3\text{BO}_3 \ \ \ \ \ \xrightarrow[-4\text{H}_2\text{O}] \ \ \ \ \ {}4\text{HBO}_2 \ \ \ \ \ \xrightarrow[-\text{H}_2\text{O}]{411\text{k}} \ \ \ \ \ \text{H}_2\text{B}_4\text{O}_7 \ \ \ \ \ \xrightarrow[-\text{H}_2\text{O}]{\text{Red hot}} \ \ \ \ \ 2\text{B}_2\text{O}_3 \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Metaboric acid} \ \ \ \ \ \ \ \ \ \ \ \text{Tetraboric acid} \ \ \ \ \ \ \ \ \ \ \ \text{Boron trioxide}$
View full question & answer→MCQ 111 Mark
Boric acid is polymeric due to :
- A
- ✓
The presence of hydrogen bonds.
- C
- D
AnswerCorrect 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.
View full question & answer→MCQ 121 Mark
Thermodynamically the most stable form of carbon is :
AnswerGraphite is thermodynamically the most stable form of carbon.
View full question & answer→Question 131 Mark
Write balanced equations for:
Al + NaOH →
Answer$2\text{Al} \ \ \ \ \ + \ \ \ \ \ \text{NaOH} \ \ \ \ \ + \ \ \ \ \ 6\text{H}_2\text{O} \ \ \ \ \ \rightarrow \ \ \ \ \ 2\text{Na}^+\big[\text{Al(OH)_4}\big]^-_{\text{(eq)}} \ \ \ \ \ + \ \ \ \ \ 3\text{H}_2 \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{Sodium tetrahydroxoaluminate (III)}$
View full question & answer→Question 141 Mark
What name is given to the compounds formed by more electropositive elements with carbon?
AnswerIonic compounds e.g. calcium carbide, $\text{Ca}^{2+}(\text{C}\equiv\text{C})^{2-}.$
View full question & answer→Question 151 Mark
Mention the state of hybridization of B in $\text{BH}^-_4.$
View full question & answer→Question 161 Mark
Are all the B-H bonds in diborane equivalent?
AnswerNo, there are two types of bonds in diborane two electron normal bonds and three centred two electron bonds.
View full question & answer→Question 171 Mark
Among tri halides of nitrogen which one is least basic and why?
Answer$\text{NF}_3$ is least basic because 'F' is most electronegative therefore lone pair of electron will be less available.
View full question & answer→Question 181 Mark
Atomic radius of gallium (135 pm) is less than that of aluminium (143 pm). Give reason.
OR
How would you justify the lower atomic radius of Ga as compared to Al?
AnswerIt is due to poor shielding effect of 3d-electrons due to which effective nuclear charge increases in Ga, therefore, it is smaller than Al.
View full question & answer→Question 191 Mark
Which allotrope of carbon is used as moderator in atomic reactors?
MCQ 201 Mark
Choose the wrong statement :
- ✓
$\mathrm{CO}_2$ and $\mathrm{SiO}_2$ both are linear in geometry.
- B
$\mathrm{SnCl}_2$ is solid, $\mathrm{SnCl}_4$ is liquid.
- C
Carborundum is $\ce{SiC}.$
- D
Zeotites can act as sieves.
AnswerCorrect option: A. $\mathrm{CO}_2$ and $\mathrm{SiO}_2$ both are linear in geometry.
View full question & answer→Question 211 Mark
Why does C differ from rest of elements?
AnswerCarbon has smallest size, highest ionisation enthalpy and high electronegativity and does not have d-orbitals, therefore, it differs from rest of the elements.
View full question & answer→Question 221 Mark
What is inert pair effect?
AnswerIn the elements of 4th, 5th and 6th period of the p-block the electrons present in the intervening dand f-orbitals do not shield the s-electrons of the valence shell effectively. As a result, $\text{ns}^2$-electrons remain more tightly held by the nucleus and hence, do not participate in bonding. This is called inert pair effect.
View full question & answer→Question 231 Mark
Out of carbon and silicon which can form multiple bond and why?
AnswerCarbon can form multiple bonds because it is smaller in size.
View full question & answer→Question 241 Mark
The colour of bead in borax bead test is mainly due to formation of which compound?
AnswerMetal metaborate e.g. $\mathrm{Co}\left(\mathrm{BO}_2\right)_2$ is blue, $\mathrm{Cr}\left(\mathrm{BO}_2\right)_3$ is green.
View full question & answer→Question 251 Mark
Why does $\text{BF}^{3-}_6$ not exist but $\text{AlF}^{3-}_6$ exist?
AnswerIt is because 'B' does not have vacant d-orbitals whereas as Al has d-orbitals of form $\text{AlF}^{3-}_6.$
View full question & answer→Question 261 Mark
Give two uses of silicones.
Answer
- They are used as sealants and electrical insulators.
- They are used in surgical and cosmetic implants because they biocompatible.
View full question & answer→Question 271 Mark
Draw the structure of the following:
- $\text{PCl}_3$
- $\text{NO}_3^-$
- $\text{P}_4$
- $\text{PCl}_5$
View full question & answer→Question 281 Mark
Mention the type of hybrid orbitals of silicon in $\text{SiF}^{2-}_6$ ion.
Answer$\text{sp}^3\text{d}^2$.
View full question & answer→Question 291 Mark
Why does boron resemble Si?
AnswerBoth have similar charge over radius ratio, i.e., similar polarising power.
View full question & answer→Question 301 Mark
What is the hybridisation of carbon in diamond?
Question 311 Mark
AnswerBoron resembles both with metals and non-metals, therefore, it is metalloid.
View full question & answer→Question 321 Mark
Name the member of group 14 that forms the most acidic oxide.
AnswerAmong monoxides, CO is neutral and GeO is acidic while among dioxides, $\mathrm{CO}_2, \mathrm{SiO}_2$ are acidic, $\mathrm{GeO}_2$ is also acidic but less acidic than $\mathrm{SiO}_2$.
View full question & answer→Question 331 Mark
C and Si are always tetravalent but Ge, Sn, Pb show divalency.
Answer$\mathrm{Ge}, \mathrm{Sn}, \mathrm{Pb}$ show divalency due to inert pair effect, $\mathrm{Pb}^{2+}$ is more stable than $\mathrm{Pb}^{4+}$.
View full question & answer→Question 341 Mark
Write the formula of inorganic benzene.
Answer$\mathrm{B}_3 \mathrm{N}_3 \mathrm{H}_6$ is formula of inorganic benzene.
View full question & answer→Question 351 Mark
A gaseous substance dissolves in water giving a pale blue solution which decolourises $\mathrm{KMnO}_4$ and oxides KI to $\mathrm{I}_2$. Identify the gaseous substance.
Answer$\mathrm{N}_2 \mathrm{O}_3$ is gaseous substance.
$\mathrm{N}_2 \mathrm{O}_3+\mathrm{H}_2 \mathrm{O} \longrightarrow 2 \mathrm{HNO}_2$ (pale blue solution)
It decolouries $\mathrm{KM}_{\mathrm{n}} \mathrm{O}_4$ oxidises $\mathrm{HNO}_2$ to $\mathrm{HNO}_3$ and gets reduced to $\mathrm{M}_{\mathrm{n}^{2+}}$ which is colourless.
$\mathrm{HNO}_2$ oxidises $\mathrm{KI}$ to $\mathrm{I}_2$ because $\mathrm{I}^{-}$is good reducing agent.
View full question & answer→Question 361 Mark
-
Name the salt of phosphorus which is used as water softener in detergents.
-
What happens when silver reacts with $\mathrm{PCl}_5$? Write chemical equation.
Answera. Sodium tri poly phosphate $\left(\mathrm{Na}_5 \mathrm{P}_3 \mathrm{O}_{10}\right)$ is used as water softener in detergents.
b. $\ce{AgCl}$ and $\mathrm{PCl}_3$ is formed,
$\text{PCl}_5+2\text{Ag}\xrightarrow{\ \ \ \ \ \ \\ }2\text{AgCl}+\text{PCl}_3.$ View full question & answer→Question 371 Mark
How will you prepare an aluminosilicate?
AnswerAluminosilicate is prepared by substituting some of the Si atoms in the three dimensional network of Sio, by Al atoms.
View full question & answer→Question 381 Mark
Arrange C-C, Ge-Ge, Si-Si, Sn-Sn in decreasing order of bond energy.
AnswerC-C > Si-Si > Ge, Si-Si, Sn-Sn.
View full question & answer→Question 391 Mark
What is the formula of kernite, an ore of boron?
AnswerFormula of kernite, $\text{Na}_2[\text{B}_4\text{O}_5(\text{OH})_4]$ or $\text{Na}_2\text{B}_4\text{O}_7.2\text{H}_2\text{O}$
View full question & answer→Question 401 Mark
Name the compound of boron which have the similar structure to graphite.
AnswerBoron nitride, (BN) resembles with graphite in structure as:
View full question & answer→Question 411 Mark
Which one is more soluble in diethyl ether, anhydrous $\mathrm{AlCl}_3$ or hydrated $\mathrm{AlCl}_3$ ? Explain in terms of bonding.
AnswerAnhydrous $\mathrm{AlCl}_3$ is an electron-deficient compound while hydrated $\mathrm{AlCl}_3$ is not. Therefore, anhydrous $\mathrm{AlCl}_3$ is more soluble in diethyl ether because the oxygen atom of ether donates a pair of electrons to the vacant p-orbital on the Al atom in $\mathrm{AlCl}_3$ forming a coordinate bond.
In case of hydrated $\mathrm{AlCl}_3, \mathrm{Al}$ is not electron deficient since $\mathrm{H}_2 \mathrm{O}$ has already donated a pair of electrons to it. View full question & answer→Question 421 Mark
Why the elements of the second row $($first short period$)$ show a number of differences in properties from other members of their respective families?
AnswerThe differences in the properties of the first member of a group from those of the other members are due to.
- The smaller size of the atom,
- Presence of one inner shell of only two electrons and.
- Absence of $d-$orbitals.
View full question & answer→Question 431 Mark
Which of the following does not produce $\mathrm{N}_2$ gas by the thermal decomposition.
$\text{Ba}(\text{N}_3)_2,(\text{NH}_4)_2\text{Cr}_2\text{O}_7,\text{NH}_4\text{NO}_2,(\text{NH}_4)_2\text{SO}_4.$
Answer$\left(\mathrm{NH}_3\right)_2 \mathrm{SO}_4$ does not give nitrogen on thermal decompositions. Others give $\mathrm{N}_2$.
$\mathrm{Ba}\left(\mathrm{~N}_3\right)_2 \xrightarrow{\text { Heat }} \mathrm{Ba}+3 \mathrm{~N}_2$
$\left(\mathrm{NH}_4\right)_2 \mathrm{Cr}_2 \mathrm{O}_7 \xrightarrow{\text { Heat }} \mathrm{Na}+\mathrm{Cr}_2 \mathrm{O}_3+4 \mathrm{H}_2 \mathrm{O}$
$\mathrm{NH}_4 \mathrm{NO}_2 \xrightarrow{\Delta} \mathrm{~N}_2+2 \mathrm{H}_2 \mathrm{O}$
View full question & answer→Question 441 Mark
Name two isotopes of boron.
Answer$^{10}\text{B}$ and $^{11}_5\text{B}$ are isotopes of boron.
View full question & answer→Question 451 Mark
Why does silicon show a higher covalency than carbon?
AnswerSi because of the presence of vacant d-orbitals can show a covalency upto six while C because of the absence of d-orbitals cannot have a covalency of more than four.
View full question & answer→Question 461 Mark
Mention two important ores of boron.
Answeri. Kermite, $\mathrm{Na}_2 \mathrm{~B}_4 \mathrm{O}_7 .2 \mathrm{H}_2 \mathrm{O}$
ii. Colemanite $\mathrm{Ca}_3 \mathrm{~B}_6 \mathrm{O}_{11} .5 \mathrm{H}_2 \mathrm{O}$
View full question & answer→Question 471 Mark
Why is crystalline boron hard solid?
AnswerIt is due to strong covalent bonds.
View full question & answer→Question 481 Mark
What is bond angles $\mathrm{Cl}-\mathrm{P}-\mathrm{Cl}$ in $\mathrm{PCI}_5$ ?
Answer$120^\circ$ and $90^\circ$
View full question & answer→Question 491 Mark
Mention the basic unit of all silicates.
Answer$\text{SiO}_4^{2-}$ is basic unit of all silicates.
View full question & answer→Question 501 Mark
Arrange the hydrides of group 14 in increasing order of reducing power.
Answer$\text{CH}_4<\text{SiH}_4<\text{GeH}_4<\text{SnH}_4<\text{Pb}$
View full question & answer→Question 511 Mark
Why does gallium undergo disproportionation reactions?
AnswerGallium shows both +1 and +3 oxidation states due to inert pair effect. However, its +3 oxidation state is more stable than +1 oxidation state, hence undergoes disproportionation to form gallium and more stable +3 gallium ions in aqueous solution as shown below.
or $3\text{Ga}^+(\text{aq})\xrightarrow{\ \ \ \ \ \ \ \ \ }2\text{Ga}(\text{s})+\text{Ga}^{3+}(\text{aq})$ View full question & answer→Question 521 Mark
Silicones are used for making waterproof fabrics. Give reason.
AnswerSilicones are synthetic polymers containing repeated units of $\mathrm{R}_2 \mathrm{SiO}$ where R is alkyl group.Therefore, these are water repellants i.e. do not absorb water and are used for making waterproof fabrics.
View full question & answer→Question 531 Mark
- Why is $\mathrm{PCl}_5$ known but $\mathrm{Pl}_5$ is not?
- Red phosphorus is denser than white phosphorus, why?
Answer
- $'Cl'$ is small in size as compared to $I$, therefore fire $CI$ atoms can be easily accommodated around $‘P\ '$ atom but five bigger $I$ atoms can not be accommodate due to stearic henderace. $P-I$ bond is weaker than $P-Cl$ bond.
- Red phosphorus has polymeric structure and more inter molecular force of attraction as compared to white phosphorus $($monomeric$)$, therefore, it is denser.
View full question & answer→Question 541 Mark
Give one example of zeolite.
AnswerFeldspar $\left(\mathrm{KAISi}_3 \mathrm{O}_8\right)$, Zeolite $\left(\mathrm{NaAlSi}_2 \mathrm{O}_6 \cdot \mathrm{H}_2 \mathrm{O}\right)$
View full question & answer→Question 551 Mark
Why is $\mathrm{B}-\mathrm{X}$ bond distance in $\mathrm{BX}_3$ shorter than the theoretically expected value?
AnswerThis is due to pπ-pπ back bonding of the completely filled p-orbital of halogen X into the empty p-orbital of boron.
View full question & answer→Question 561 Mark
Why the tri halide of group 13 elements fume in moist air?
AnswerBoron forms only covalent compounds because it does not form $\text{B}^{3+}$ ion. High energy is required to remove 3 electrons.
View full question & answer→Question 571 Mark
$\mathrm{AlF}_3$ is high melting solid but $\mathrm{AlCl}_3$ is low melting. Explain.
Answer$\mathrm{AlF}_3$ is high melting solid because it is ionic in nature. On the other hand, $\mathrm{AICI}_3$ is covalent in nature and hence is a low melting solid.
View full question & answer→Question 581 Mark
- Why is electron gain enthalpy of group $15$ less than group $16$ ?
- Nitric oxide becomes brown when released in air, why?
Answer
- It is because group $15$ have outer electronic configuration $\ce{ns^2 np^3}$ i.e. half filled p-orbitals which are more stable, therefore, have least tendency to gain electron as compared to group $\ce{16 (ns^2 - np^4)}$
- Nitric oxide reacts with air to form nitrogen dioxide which is brown in colour.
$2\text{NO}(\text{g})+\text{O}_2(\text{g})\xrightarrow{\ \ \ \ \ \ \ \ \ }2\text{NO}_2(\text{g})$ View full question & answer→Question 591 Mark
a. $\mathrm{Bi}_2 \mathrm{O}_3$ is treated with $\mathrm{HNO}_3$. Write balanced equation for the reaction.
b. Why does Bismuth not form pentahalide?
Answer
- $\text{BI}_2\text{O}_3+6\text{HNO}_3\xrightarrow{\ \ \ \ \ \ \ \ \ \ }2\text{Bi}(\text{NO}_3)_3+3\text{H}_2\text{O}$
- $\mathrm{Bi}^{3+}$ is more stable than $\mathrm{Bi}^{5+}$, therefore Bismuth does not penta$-$halide.
View full question & answer→Question 601 Mark
Although pure silicon is an insulator, then how does it behave as semiconductor on heating?
AnswerSilicon becomes semiconductor on heating because electrons become free to move.
View full question & answer→Question 611 Mark
Name the elements of group 13 which forms only covalent compounds.
AnswerBoron forms only covalent compounds because it does not form $\text{B}^{3+}$ ion. High energy is required to remove 3 electrons.
View full question & answer→Question 621 Mark
Why is $\mathrm{BF}_3$ weaker Lewis acid than $\mathrm{BCI}_3$ ?
Answer$\mathrm{BF}_3$ is weaker Lewis acid than $\mathrm{BCl}_3$ because of more effective back bonding in case of F due to smaller size than Cl.
View full question & answer→Question 631 Mark
Why $\mathrm{SnCl}_4$ is more covalent than $\mathrm{SnCl}_2$ ?
AnswerIt is because $\mathrm{Sn}^{4+}$ has more polarizing power, therefore, more tendency to form covalent bond than $\mathrm{Sn}^{2+}$.
View full question & answer→Question 641 Mark
$\mathrm{NaCl}_3$ gets hydrolysed while $\mathrm{NF}_3$ does not, why?
AnswerIn $\mathrm{NCl}_3$, 'Cl' has vacan d-orbitals to accept a lone pair of electrons Donated by O of $\mathrm{H}_2 \mathrm{O}$, molecule but in $\mathrm{NF}_3$, 'F' does not d-orbitals.
$\text{NCl}_3+3\text{H}_2\text{O}\xrightarrow{\ \ \ \ \ }\text{NH}_3+3\text{HCl}$
$\text{NF}_3+\text{H}_2\text{O}\xrightarrow{\ \ \ \ \ \ \ \ }\text{No reaction}$.
View full question & answer→Question 651 Mark
- Why does tendency to show catenation decreases down the group?
- Why is $\mathrm{N}_2 \mathrm{O}$, more acidic than $\mathrm{N}_2 \mathrm{O}_3$ ?
Answer
- It is because bond dissociation enthalpy decreases due to increase in bond length with the increase in atomic size of element.
- Higher the oxidation state, more will be acidic character, that is why $\mathrm{N}^2 \mathrm{O}^5$ is more acidic than $\mathrm{N}_2 \mathrm{O}_3$.
View full question & answer→Question 661 Mark
Write the formula of dry ice.
AnswerDry ice is solid $\mathrm{CO}_2$ in which there are van der Wall's forces of attraction.
View full question & answer→Question 671 Mark
Why does boron trifluoride behave as Lewis acid?
AnswerIt is because 'B' shares three electrons with fluorine and its octet is not complete, therefore, it behaves as Lewis acid.
View full question & answer→Question 681 Mark
Which of the following is acidic and why?
$\mathrm{SiO}_2, \mathrm{Al}_2 \mathrm{O}_3, \mathrm{PbO}_2, \mathrm{SnO}_2$
Answer$\mathrm{SiO}_2$ is acidic oxide because Si shows non-metallic properties. $\mathrm{Al}_2 \mathrm{O}_3, \mathrm{PbO}_2$ and $\mathrm{SnO}_2$ are amphoteric.
View full question & answer→Question 691 Mark
What is formula of Forstrite?
Answer$\mathrm{Mg}_2 \mathrm{~SiO}_2$ (magnesium silicate)
View full question & answer→Question 701 Mark
Why does boron not form $\text{B}^{3+}$ ion?
AnswerBoron does not form $\text{B}^{3+}$ ion due to smallest atomic size and highest ionisation enthalpy.
View full question & answer→Question 711 Mark
What are germanes and plumbares?
AnswerBoron resembles both with metals and non-metals, therefore, it is metalloid.
View full question & answer→Question 721 Mark
Why is diamond a bad conductor of electricity but a good conductor of heat?
AnswerConduction of electricity essentially requires movement of electrons while conduction of heat does not necessarily require movement of electrons.
View full question & answer→Question 731 Mark
$\mathrm{TI}\left(\mathrm{NO}_3\right)_3$ acts as an oxidising agent Explain.
AnswerDue to inert pair effect, Tl in +1 oxidation state is more stable than that of +3 oxidation state. Therefore, $\mathrm{TI}\left(\mathrm{NO}_3\right)_3$ acts as an oxidising agent and readily reduced to $\mathrm{TINO}_3$.
View full question & answer→Question 741 Mark
Which of the following are Lewis acids:
$\text{PH}_3,\text{BCl}_3,\text{AlCl}_3,\text{SiCl}_4.$
Answer$\mathrm{BCl}_3$ and $\mathrm{AlCl}_3$ are Lewis acid because their octet is not complete.
View full question & answer→
