1.Brass gets discoloured in air because of the presence of which of the following gases in air?

A. Oxygen B. Hydrogen sulphide C. Carbon dioxide D. Nitrogen

Tear gas is

(A) Ammonia

(B) Hydrogen sulphide

(C) Chlorine

(D) Hydrogen chloride

In coloured glass. the purple colour is imparted by

(A) Manganese oxide

(B) Cadmium sulphide

(C) Ferric oxide

(D) Selenium sulphide

1. Radiocarbon is produced in the atmosphere as a result of

A. collision between fast neutrons and nitrogen nuclei present in the atmosphere

B. action of ultraviolet light from the sun on atmospheric oxygen

C. action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere

D. lightning discharge in atmosphere