${\mathrm{H}}_3{\mathrm{BO}}_3$ 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.

Incorrect order among the following is:

The basic structural unit of silicates is-

A solid (A) reacts with strong aqueous NaOH, liberating a foul smelling gas (B), which spontaneously burns in the air, giving smoky rings. A and B are, respectively:

1. P₄ (red) and PH₃ 

2. P₄ (white) and PH₃

3. S₈ and H₂S

4. P₄ (white) and H₂S

Identify the correct statements among the following:

a. ${\mathrm{CO}}_2\left(\mathrm{g}\right)$ is used as a refrigerant for ice-cream and frozen food.

b. The structure of ${\mathrm{C}}_{60}$ contains twelve six-carbon rings and twenty five-carbon rings.

c. ZSM-5, a type of zeolite, is used to convert alcohol into gasoline.

d. CO is a colourless and odourless gas

1. (a) and (c) only

2. (b) and (c) only

3. (c) and (d) only

4. (a), (b) and (c) only

The reason behind carbon showing catenation property but lead does not is:

1. Due to the smaller size of C than that of Pb

2. Due to the smaller size of Pb than that of C

3. Due to the smaller ionization energy of C than that of Pb

4. Due to the inert pair effect

The disproportionation reaction of ${\mathrm{H}}_3{\mathrm{PO}}_3$ is as follows:

${\mathrm{H}}_3{\mathrm{PO}}_3$ $\stackrel{∆}{\to }$ $\mathrm{X}$ $+$ $\mathrm{Y}$

 X and Y in the above reaction are:

1. H₃PO₂, HPO₂  

2. H₃PO₄, PH₃

3. H₂PO₆, PO₃

4. None of the above.

The compound among the following with the lowest pK_a value is?

1. H₂O

2. H₂S

3. H₂Se

4. H₂Te

The condition that does not exist in the Haber process for the manufacturing of ammonia is:

1. Pressure (around 200 ×10⁵ Pa)
2. Temperature (700 K)
3. Catalyst such as iron oxide.
4. Presence of inert gases.

In diborane, the two H-B-H angles are nearly-

1. $60°,$ $120°$

2. $97°,120°$

3. $97°,150°$

4. $120°,$ $180°$