21. Ponds look shallow because of: Refraction

22. Short-sight in human eye can be rectified by:
Concave lens

23. Sound frequency below 20 Hz is called: Infrasonic

24. The Automated Teller Machine (ATM) was invented
by: John Shepard Barren

25. The density of air is: 1.3 kg /cubic metre

26. The electromagnetic waves do not transport: Information

27. The energy absorbed during the change of a state
of substance is called: Latent heat

28. The energy that travels through telephone line: Electrical energy

29. The expected energy of electrones at absolute zero
is called: Fermi Energy

30. The first ballistic missile was developed under direction of : Wernher von Braun