The effect of heating Boric acid at 370 K or above is -

1. Orthoboric acid changes to metaboric acid.

2. Metaboric acid changes to boric oxide.

3. Both '1' and '2'

4. Neither '1' nor '2'

The shapes of ${\mathrm{BF}}_3 \mathrm{and} \mathrm{B}{{\mathrm{H}}_4}^{-}$ and the hybridization of boron in these species are respectively -

1. ${\mathrm{BF}}_3$ - triangular geometry, ${\mathrm{sp}}^2$; $\mathrm{B}{{\mathrm{H}}_4}^{-}$- tetrahedral, ${\mathrm{sp}}^3$

2. ${\mathrm{BF}}_3$ - tetrahedral, ${\mathrm{sp}}^2$; $\mathrm{B}{{\mathrm{H}}_4}^{-}$ - triangular geometry, ${\mathrm{sp}}^3$

3.  ${\mathrm{BF}}_3$ - tetrahedral, ${\mathrm{sp}}^3$ ; $\mathrm{B}{{\mathrm{H}}_4}^{-}$ - triangular geometry, $s{p}^3$

4. ${\mathrm{BF}}_3$ - tetrahedral, ${\mathrm{sp}}^2$ ; $\mathrm{B}{{\mathrm{H}}_4}^{-}$ - triangular geometry, ${\mathrm{sp}}^2$

Reaction(s) that justify the amphoteric nature of aluminum is-

$1. 2\mathrm{Al}\left(\mathrm{s}\right) + 6\mathrm{HCl}\left(\mathrm{aq}\right) \to 2{\mathrm{Al}}^{+3}\left(\mathrm{aq}\right) + 6{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right) + 3{\mathrm{H}}_2\left(\mathrm{g}\right)$​

$2. 2\mathrm{Al}\left(\mathrm{s}\right) + 2\mathrm{NaOH}\left(\mathrm{aq}\right) + 6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \to 2\mathrm{Na}\left[\mathrm{Al}{\left(\mathrm{OH}\right)}_4{]}^{-}\right(\mathrm{aq}) +3{\mathrm{H}}_2(\mathrm{g})$​

3. Both '1' and '2'

4. Neither '1' nor '2'

The electron-deficient compound among the following is -

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

The B–F bond lengths in ${\mathrm{BF}}_3$ (130 pm) and $\mathrm{B}{{\mathrm{F}}_4}^{-}$(143 pm) differ because of:

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:

CO is a poisonous gas because :

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

The sharp decrease in ionization enthalpy from carbon to silicon happens because of-