21 The ratio of the speed of sound in steel to its speed in air is

15 : 1

22 Anti-polio vaccine was discovered by

Jonas E. Salk

23 Exobiology is the study of

Life or its possibility on other planets

24 Anti-matter is

Anti-particles constituting nuclei of anti-protons and orbital positrons

25 The electric device that would transmit sound as well as image is called

Videophone

26 Typical vertebrates have tails but humans do not have one. What is the reason?

Man had a tail but it was lost during development

27 Weathering is

Decomposition of rocks

28 Larynx is also called

The Adam’s Apple

29 Anti-rabies treatment was evolved by

Louis Pasteur

30 Hydroponics is the art of

Growing plants without soil