What is the effect of heating H₃BO₃ at 370 K and above?

1. Orthoboric acid changes to metaboric acid.

2. Metaboric acid changes to boric oxide.

3. Both '1' and '2'

4. Neither '1' nor '2'

Which of the following compounds is electron-deficient?

1. ${\mathrm{SiCl}}_4$

2. ${\mathrm{BCl}}_3$

3. ${\mathrm{PCl}}_3$

4. $\mathrm{ICl}$

The hybridization of carbon in (a) ${\mathrm{CO}}_3^{2-}$ (b) diamond (c) graphite is respectively:

1. ${\mathrm{sp}}^2$, ${\mathrm{sp}}^3$, ${\mathrm{sp}}^2$

2. ${\mathrm{sp}}^2$, ${\mathrm{sp}}^3$, $s{p}^3$

3. ${\mathrm{sp}}^3$, ${\mathrm{sp}}^3$, ${\mathrm{sp}}^2$

4. ${\mathrm{sp}}^3$, ${\mathrm{sp}}^2$, ${\mathrm{sp}}^3$

Why is the B–F bond length in BF₃ (130 pm) shorter than that in BF₄⁻ (143 pm)?

1. Presence of triple-bond character in ${\mathrm{BF}}_3$

2. Resonance in $\mathrm{B}{{\mathrm{F}}_4}^{-}$

3. Presence of a double-bond character in ${\mathrm{BF}}_3$

4. Presence of a double bond character in $\mathrm{B}{{\mathrm{F}}_4}^{-}$

Despite the dipole moment in the B–Cl bond, the BCl₃ molecule as a whole has no dipole moment because:

Why carbon monoxide (CO) is poisonous?

An excessive content of CO₂ is responsible for global warming as:

The first ionization enthalpy decreases sharply from carbon to silicon in Group 14. What is the main reason for this decrease?

Which of the following best explains why the atomic radius of gallium is smaller than that of aluminium?

1. Poor shielding effect of the 2d-electrons

2. Poor shielding effect of the 3d-electrons

3. Poor shielding effect of the 3p-electrons

4. Poor shielding effect of the 2s-electrons

Identify the pair in which both oxides are amphoteric in nature.

1. Tl₂O₃, SiO₂

2. ${\mathrm{CO}}_2$, ${\mathrm{B}}_2{\mathrm{O}}_3$

3. ${\mathrm{B}}_2{\mathrm{O}}_3$, ${\mathrm{SiO}}_2$

4. Al₂O₃ , PbO₂