The respective oxidation states of P in H₄P₂O₅, H₄P₂O₆, and H₄P₂O₇ are: 

1.	+3, +5, and +4	2.	+5, +3, and +4
3.	+5, +4, and +3	4.	+3, +4, and +5

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

Incorrect order among the following is:

The number of \(\mathrm{S=O}\) bonds present in \(\mathrm{H}_2\mathrm{S}_2 \mathrm{O}_8\) is:

A balanced chemical equation for the reaction showing catalytic oxidation of NH₃ by atmospheric oxygen is:

The correct structure of pyrophosphoric acid is:

1.		2.
3.		4.

PH₃ forms bubbles when passed slowly through water but NH₃ gets dissolved in water, because: 

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 correct increasing order of basic strength of hydrides:

1. BiH₃ \(\simeq \) SbH₃ < AsH₃ < PH₃ < NH₃ 
2.  BiH₃  > NH₃  > PH₃ > SbH₃ > AsH₃ 
3. SbH₃ < AsH₃ < PH₃ < NH₃ < BiH₃ 
4. AsH₃ > NH₃ > PH₃ > SbH₃ > BiH₃

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

1. H₂O

2. H₂S

3. H₂Se

4. H₂Te