(A) Complete the following chemical equations :
(i) `Cu+HNO_(3)` (dilute) `to`
(ii) `XeF_(4)+O_(2)F_(2)to`
(B) Explain the following observations:
(i) Phosphorous has greater tendency for catenation than nitrogen.
(ii) Oxygen is a gas but sulphur is a solid.
(iii) The halogens are coloured. Why ?

Explanation

(a) (i) `3Cu + 8HNO_(3)` (dilute) `to Cu(NO_(3))_(2) + 2NO + 4H_(2)O`
(ii) `XeF_(4) + O_(2)F_(2) overset(143K)(to) XeF_(6)O_(2).`
(b) (i) Phosphorus has greater tendency for catenation than nitrogen . Due to greater bond strength of P-P single than N-N single bond .
(ii) Oxygen is a gas but sulphur a solid. Sulphur because of its bigger size and lower electronegatively , prefers to form S-S single bonds . Further because of stronger S-S than O-O single bonds , sulphur has a much greater tendency for catenation than oxygen .
(iii) Halogen are coloured . It is due to reason that their molecules absorb light in the visible region as a result of which their electrons get excited to higher energy levels while the remaining light is transmitted.