771.

Among the hydrides of Group-15 elements, which have the

1. Lowest boiling point?
2. Maximum basic character?
3. Highest bond angle?
4. Maximum reducing character?

Give reasons:

H₃PO₃ undergoes disproportionation reaction but H₃PO₄ does not.

Give Reason:

Dioxygen is a gas while Sulphur is a solid at room temperature.

Draw the structures of the following.
(i) XeF₄
(ii) HClO₃

When concentrated sulphuric acid was added to an unknown salt present in a test tube a brown gas (A) was involved. This gas intensified when copper turnings were added to this test tube. On cooling, the gas (A) changed into a colourless solid (B).
(i) Identify (A) and (B)
(ii) Write the structures of (A) and (B)
(iii) Why does gas (A) change to solid on cooling

Arrange the following in the decreasing order of their reducing character:

HF, HCl, HBr, HI

Complete the following reaction:
xeF4 + SbF5 -->

Oxidation number of nitrogen in which among the oxides of nitrogen is the lowest?

• Nitric oxide

• Nitrous oxide

• Nitrogen dioxide

• Nitrogen trioxide

The reaction of zinc with dilute and concentrated nitric acid, respectively, produces:

• NO₂ and NO

• NO and N₂O

• NO₂ and N₂O

• NO₂ and N₂O

Which one has the highest boiling point?

• He

• Ne

• Kr

• Kr