${}_{}$
\(\mathrm{Al}_2 \mathrm{O}_3\) reacts with-

1.	Only water	2.	Only acids
3.	Only alkalis	4.	Both acids and alkalis

${\mathrm{}}_{}$
Which of the following reactions cannot be used for the preparation of diborane, B₂H₆?

1. ${\mathrm{NaBH}}_4$ $$ $+$ ${\mathrm{I}}_2$ $\to$

2. ${\mathrm{BF}}_3$ $$ $+$ $\mathrm{NaH}$ $\to$

3. ${\mathrm{B}}_3{\mathrm{N}}_3{\mathrm{H}}_6$ $$ $+$ ${\mathrm{H}}_2\mathrm{O}$ $\to$

4. ${\mathrm{Mg}}_3{\mathrm{B}}_2$ $+$ $\mathrm{dil}$ $\mathrm{HCl}\to$

The most characteristic oxidation state for lead and tin is, respectively,:

1. +4, +2

2. +2, +4

3. +4, +4

4. +2, +2

${\mathrm{}}_{}$
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.

Find the anion that cannot be formed by boron.
1. [BF₆]³⁻
2. BH₄⁻
3. B(OH)₄⁻
4. BO₂⁻

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

Identify the correct statements among the following:

1. (a) and (c) only

2. (b) and (c) only

3. (c) and (d) only

4. (a), (b) and (c) only

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.

Assertion: Boron always forms a covalent bond.

Reason: Boron has a diagonal relationship with silicon.

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.

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.