Which of the following  hydrides has the lowest pKa value?

1. H₂O

2. H₂S

3. H₂Se

4. H₂Te

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

1. $60°,$ $120°$

2. $97°,120°$

3. $97°,150°$

4. $120°,$ $180°$

Which of the following molecules have the same number of lone pairs of electrons on the central Xe atom?

(i) XeO₃
(ii) XeOF₄
(iii) XeF₆

1. (i) and (ii) only

2. (i) and (iii) only

3. (ii) and (iii) only

4. (i), (ii), and (iii) only

A compound "X", upon reaction with H₂O, produces a colourless gas "Y" with a rotten fish smell.  Gas 'Y' is absorbed in a solution of CuSO₄ to give Cu₃P₂ as one of the products. The compound 'X' will be:

1. Ca₃P₂

2. ${\mathrm{NH}}_4\mathrm{Cl}$

3. ${\mathrm{As}}_2{\mathrm{O}}_3$

4. Ca₃(PO₄)₂

Aluminium chloride in acidified aqueous solution forms a complex 'A'.
The formula of A and hybridisation state of Al in 'A' is respectively:

1. [Al(H₂O)₆]³⁺, sp³d²

2. [Al(H₂O)₄]³⁺, sp³

3. [Al(H2O)4]3+, dsp2

4. [Al(H₂O)]³⁺, d²sp³

Which of the following orders is incorrect for the given properties of halogens?

${\mathrm{H}}_3{\mathrm{BO}}_3$ 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.

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

Which of the following statements regarding the stability of lead and tin compounds is incorrect?

1. ${\mathrm{PbX}}_2$ is more stable than ${\mathrm{PbX}}_4$

2. ${\mathrm{PbCl}}_4$ is less stable than ${\mathrm{SnCl}}_4$ but ${\mathrm{PbCl}}_2$ is more stable than ${\mathrm{SnCl}}_2$

3. ${\mathrm{PbCl}}_4$ is less stable than ${\mathrm{SnCl}}_4$

4. Pb(II) is a good reducing agent while Sn(II) is not