Give reasons for the following:
(i) (CH₃)3P = O exists but (CH₃)₃N = O does not.
(ii) Oxygen has less electron gain enthalpy with the negative sign than sulphur.
(iii) H₃PO₂ is a stronger reducing agent than H₃PO₃.

Complete the following reactions :
NH₃ + 3Cl₂(excess) →

Complete the following reactions :
XeF₆ + 2H₂O → 

764.

What happens when
H₃PO₃ is heated?

Draw the structures of the following :
H₂S₂O₇

Draw the structures of the following :
XeF₆

Give reasons:
Thermal stability decreases from H₂O to H₂Te.

Give reasons:
Fluoride ion has higher hydration enthalpy than chloride ion.

Give reasons:
Nitrogen does not form pentahalide.

How is the variability in oxidation states of transition metals different from that of the p-block elements?