Assertion: B-X bond length in ${\mathrm{BX}}_3$ is shorter than the expected value.

Reason: $p\mathrm{\pi }-\mathrm{p\pi }$ back bonding occurs between B and X.

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.

${\mathrm{H}}_3{\mathrm{BO}}_3$ is -

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.

Carbon dioxide is a gas but silica is a solid because:

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.

When silicon is boiled with caustic soda solution, the gas is evolved is-

1. ${\mathrm{O}}_2$

2. ${\mathrm{SiH}}_4$

3. ${\mathrm{H}}_2$

4. None of the above

The basic structural unit of silicates is-

A compound among the following that is not a monomer for a high molecular mass silicone polymer is-

1. ${\mathrm{Me}}_3\mathrm{SiCl}$

2. ${\mathrm{PhSiCl}}_3$

3. ${\mathrm{MeSiCl}}_3$

4. ${\mathrm{Me}}_2{\mathrm{SiCl}}_2$

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 -

Ionization enthalpy (${∆}_{\mathrm{i}}{\mathrm{H}}_1\mathrm{kJ} {\mathrm{mol}}^{-1}$) for the elements of Group 13 follows the order.

Aluminium reacts with concentrated HCl and concentrated NaOH to liberate which of the following gases respectively-

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