531: Mycorrhiza is a symbiotic association between
(a) Bacteria and roots of higher plants
(b) Algae and roofs of orchids
(c) Fungi and roots of higher plants
(d) Protozoa and roots of higher plants
532: In the given figure, angle OQP = 30° and angle ORP = 20°, angle QOR is equal to
(a) 100°
(b) 120°
(c) 130°
(d) 140°
533: Who among the following invented Lasers?
(a) Theodore Maiman
(b) William Morton
(c) Francis Crick
(d) Denis Papin
534: 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
535: The term 'Goldilocks Zone' is often seen in the news in the context of
(a) the limits of habitable zone above the surface of the Earth
(b) regions inside the Earth where shale gas is available
(c) search for the Earth-like planets in outer space
(d) search for meteorites containing precious metals