413. Which is the source of cork ?
(a) Corica papaya
(b) Silver oak
(c) Quercus suber
(d) Cyprus plant
414. X-rays are
(a) Flows of electrons
(b) Electromagnetic radiations
(c) Streams of charged atoms
(d) Streams of electrons and protons
415. Nagarjuna whose works were found in China and Tibet was
(a) A chemist
(b) A mathematician
(c) A physicist
(d) A physician
416. Which of the following helps in the clotting of blood ?
(a) Vitamin A
(b) Vitamin B
(c) Vitamin K
(d) Vitamin D
417. The disease which is believed to be hereditary is
(a) Nephritis
(b) Diabetes
(c) Night blindness
(d) Anaemia
418. Cinnabar is an ore of
(a) Aluminium
(b) Copper
(c) Mercury
(d) Zinc
419. The coil of an electric heater is made of
(a) Zinc
(b) Nichrome
(c) Brass
(d) Copper
420. The level of glucose in the blood of a human being is kept constant by
(a) The action of insulin
(b) The action of liver
(c) The action of glucose
(d) The joint action of insulin and glucose
421.Nitric acid does not react with
(a) Zinc
(b) Gold
(c) Silver
(d) Copper
422.Rusting of iron in the moist air involves
(a) The hydration of iron
(b) The loss of electrons by iron
(c) Neither the loss nor the gain of electrons by iron
(d)The gain of electrons by iron