Give reasons for the following observations :
(a) A deal is formed at the meeting point of sea water and river water.
(b) `NH_(3)` gas adsorbs more readily than `N_(2)` gas on the surface of charcoal.
(c ) Powdered substances are more effective adsorbents.

Explanation

(a) For answer, consult section 26.
(b) Because criticaal temperature of `NH_(3)(406K)` is more than that of `N_(2)(126K).` For details, consult section 3.
(c ) Adsorption is a surface phenomenon and the extent of adsorption is linked with the surface area of adsorbent. Since powdered adsorbents have more surface area available, these are more effective as adsorbents.