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

1.	4NH3 + \(\underset{\text{From air}}{5O_2} \)   \(\xrightarrow[\text{500 K; 9 bar}]{\text{Pt / Rh gauge catalyst}}\)   4NO + 6H2O
2.	3NH4 + \(\underset{\text{From air}}{5O_2} \)  \(\xrightarrow[\text{500 K; 9 bar}]{\text{Pt / Rh gauge catalyst}}\)  3NO + 6H2O
3.	4NH3 + \(\underset{\text{From air}}{5O_2} \)  \(\xrightarrow[\text{cold}]{\text{no catalyst}}\)  4NO + 6H2O
4.	3NH4 + \(\underset{\text{From air}}{5O_2} \)  \(\xrightarrow[\text{cold}]{\text{no catalyst}}\)  3NO + 6H2O

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: 

All the five bonds of PCl₅ are not equivalent because:

Nitrogen dioxide is paramagnetic in a gaseous state but diamagnetic in solid because:

The correct statement regarding the bond angle of H₂O and H₂S is:

1. Both have the same bond angle.

2. Bond angle of H₂O is larger than that of H₂S

3. Bond angle of H₂O is smaller than that of H₂S 

4. None of the above.

An amorphous solid“A” burns in the air to form a gas “B” which turns lime water milky. The gas is also produced as a by-product during the roasting of sulphide ore. This gas decolourises acidified aqueous KMnO₄ solution and reduces Fe³⁺ to Fe²⁺. The solid "A" and the gas "B" are:

1. 'A' = S₈: ‘B' = SO₂

2. 'A' = S₈: ‘B' = SO₃

3. 'A' = S₁₀: ‘B' = SO₂

4. Not predictable

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 catalyst that is used in the contact process is:

The chemical formula of oleum is -