Why is CO₂ a gas at room temperature whereas SiO₂ is a solid?

1. Carbon dioxide is composed of discrete covalent ${\mathrm{CO}}_2$ molecules whereas silica has a continuous tetrahedral structure.

2. ${\mathrm{CO}}_2$ molecules are lighter than ${\mathrm{SiO}}_2$ molecules.

3. ${\mathrm{CO}}_2$ is more acidic than ${\mathrm{SiO}}_2$.

4. The melting point of silica is very high.

Assertion: The B–X bond lengths in boron trihalides (BX₃) are shorter than those expected for
                   pure B–X single bonds.

Reason: $\mathrm{p\pi –p\pi \; back-bonding\; occurs\; between\; the\; halogen\; atoms\; and\; the\; boron\; atom\; in\; BX₃.}$

1. Both Assertion & Reason are true and the reason is the correct explanation of the assertion.
2. Both Assertion & Reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is a true statement, but Reason is false.
4. Both Assertion and Reason are false statements.

A compound X, of boron, reacts with ${\mathrm{NH}}_3$ on heating to give another compound Y which is called inorganic benzene. The compound X can be prepared by treating ${\mathrm{BF}}_3$ with Lithium aluminium hydride. The compounds X and Y are represented by the formulas -

Which of the following represents the correct order of first ionization enthalpy
(ΔᵢH₁, in kJ mol⁻¹) among Group 13 elements?

Select the correct statement(s) regarding the following reaction sequence:

 
   

1.  The compound (A) is ${\left({\mathrm{CH}}_3\right)}_2{\mathrm{SiCl}}_2$

2.  The compound D is SiC

3.  The compound (B) is ${\left({\mathrm{CH}}_3\right)}_2\mathrm{Si}{\left(\mathrm{OH}\right)}_2$

4.  All of the above

Which of the following products are formed when lead nitrate, Pb(NO₃)₂, is heated?

Which option correctly represents the two H–B–H bond angles found in diborane?

1. $60°,$ $120°$

2. $97°,120°$

3. $97°,150°$

4. $120°,$ $180°$

Aluminium chloride in acidified aqueous solution forms a complex 'A'.
The formula of A and hybridisation state of Al in 'A' is respectively:

1. [Al(H₂O)₆]³⁺, sp³d²

2. [Al(H₂O)₄]³⁺, sp³

3. [Al(H2O)4]3+, dsp2

4. [Al(H₂O)]³⁺, d²sp³

${\mathrm{}}_{}$
Which of the following correctly describes the acidic nature of H₃BO₃?

1. A Monobasic acid and a weak Lewis acid.

2. A Monobasic and a weak Bronsted acid..

3. A Monobasic and a strong Lewis acid.

4. A Tribasic and a weak Bronsted acid.

Quartz is made of silicon and oxygen joined in a network arrangement that is similar to:

1. Diamond

2. Graphite

3. $O_2$

4. None of the above