4.The gas usually filled in the electric bulb is?

A. nitrogen B. hydrogen C. carbon dioxide D. oxygen

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

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

• An analysis of a compound shows that it contains 19.8 g. of Carbon, 2.50 g. of Hydrogen, and 11.6 g of Nitrogen. What is the percentage composition of C, H, O?