Why does BF₃ act as a Lewis acid?

1. Boron trifluoride is electron-rich.

2. Boron trifluoride is electron-deficient.

3. Boron trifluoride is highly stable.

4. None of the above

Which of the following statements correctly explains the difference in the hydrolysis of BCl₃ and CCl₄?

1. BCl₃ undergoes hydrolysis readily, whereas CCl₄ resists hydrolysis.

2. CCl₄ undergoes hydrolysis readily, whereas BCl₃ resists hydrolysis.

3. Both BCl₃ and CCl₄ undergo hydrolysis readily.

4. Neither BCl₃ nor CCl₄ undergoes hydrolysis.

Find the correct nature of boric acid, H₃BO₃:

1. Protic acid.

2. Weak monobasic acid.

3. Lewis acid.

4. Both '2' and '3'

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'

The shapes of ${\mathrm{BF}}_3<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>\mathrm{B}{{\mathrm{H}}_4}^{-}$ 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-

$1.<mspace\; width="1em"></mspace>2\mathrm{Al}\left(\mathrm{s}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>6\mathrm{HCl}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>\to 2{\mathrm{Al}}^{+3}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>6{\mathrm{Cl}}^{-}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>3{\mathrm{H}}_2\left(\mathrm{g}\right)$​

$2.<mspace\; width="1em"></mspace>2\mathrm{Al}\left(\mathrm{s}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2\mathrm{NaOH}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)<mspace\; width="1em"></mspace>\to <mspace\; width="1em"></mspace>2\mathrm{Na}\left[\mathrm{Al}{\left(\mathrm{OH}\right)}_4{]}^{-}\right(\mathrm{aq})<mspace\; width="1em"></mspace>+3{\mathrm{H}}_2(\mathrm{g})$​

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: