The presence of soluble fluoride ion upto 1 ppm concentration in drinking water, is :

The condition that indicates a polluted environment is :

The processes of calcination and roasting in metallurgical industries, respectively, can Iead to :

The incorrect statement(s) among (a) – (d) regarding acid rain is (are) :

(a) It can corrode water pipes.
(b) It can damage structures made up of stone.
(c) It cannot cause respiratory ailments in animals.
(d) It is not harmful for trees