22. The source of solar energy is ?
Ans Nuclear energy
23. If an object is placed midway between two parallel plane mirrors facing each other, then the number of images that appear in mirrors is
24. In vacuum , What will be common among X rays visible light , radiowaves
25. Barometer is used to measure
Ans Atmospheric pressure
26. If u use a microscope to watch smoke particles in still air, u ll see them moving about all the time. This phenomenon is called ?
Ans Brownian movement
27. The mass of a neutron is approximately
Ans Equal to the mass of proton
28. The spherical shape of rain drops is due to
Ans Atmospheric friction of air
29. Galvanometer is an instrument
Ans For measuring currents of small magnitude
30. Which of the following has highest frequency?
Ans Gamma rays