261: Assertion (A) :
Sodium metal is stored under kerosene.
Reason (R):
Metallic sodium melts when exposed to air.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is NOT a correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
262: From which one of the following did India buy the Barak anti-missile defence systems?
(a) France
(b) Israel
(c) Russia
(d) USA
263: While adding the first few continuous natural numbers, a candidate missed one of the numbers and wrote the answer as 177. What was the number missed?
(A) 13
(B) 14
(C) 12
(D) 11
264: In which of the following shapes can a 1 kg plastic sheet be moulded so as to have minimum surface area?
(a) Cylindrical
(b) Spherical
(c) Conical
(d) Cubical
265: Which one of the following types of coal contains a higher percentage of carbon than the rest ?
(a) Bituminous coal
(b) Lignite
(c) Peat
(d) Anthracite