256: Consider the following statements :
At the present level of technology available in India, solar energy can be conveniently used to
I. supply hot water to residential buildings.
II. supply water for minor irrigation projects.
III. provide street lighting.
IV. electrify a cluster of villages and small towns.
Of these statements
(a) I, II, III and IV are correct.
(b) II and IV are correct
(c) I and III are correct
(d) I, II and III are correct
257: Which substance is commonly used in refrigerators?
(a) Freon
(b) Oxygen
(c) Ammonia
(d) Sulphur dioxide
258: Diamond Ring is a phenomenon observed
(a) at the start of a total solar eclipse
(b) at the end of a total solar eclipse
(c) only along the peripheral regions of the totality trial
(d) only in the central regions of the totality trial
Explanation:
Diamond ring is a phenomenon observed only along the peripheral regions of the totality trail.
259: Municipal water in India is generally treated with:
(a) Chlorine
(b) Potassium permanganate
(c) Sodium Chloride
(d) Sodium Carbonate
260: The alpha-particle carries two positive charges. Its mass is very nearly equal to that of
(a) two protons
(b) an atom of helium
(c) sum of masses of two positrons and two neutrons
(d) two positrons as each positron carries a single positive charge
Explanation:
Alpha particle carries two positive charges. Its mass is very nearly equal to an atom of Helium. Beta particle carries one unit negative charge and its mass is equal to an electron. Gamma particle has neutral charge and no mass.