681: Consider the following statements :
Chlorofluorocarbons, known as ozone-depleting substances, are used
1. in the production of plastic foams
2. in the production of tubeless tyres
3. in cleaning certain electronic components
4. as pressurizing agents in aerosol cans
Which of the statements given above is/are correct?
(a) 1, 2 and 3 only
(b) 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4
682: The resinous substance, shellac is obtained from
(a) Crude oil
(b) The bark of a tree
(c) An insect
(d) Distillation of wood
683: Consider the following events :
I. Reign of Krishnadevaraya of Vijayanagara.
II. Construction of Qutab Minar.
III. Arrival of Portuguese in India.
IV. Death of Firoz Tughlaq.
(a) II, IV, III, I
(b) II, IV, I, III
(c) IV, II, I, III
(d) IV, II, III, I
684: Consider the map given below indicating four places:
Which one of them is Chechenys ? Choose the correct answer.
(a) 1
(b) 2
(c) 3
(d) 4
685: The light from the Sun reaches the Earth in about
(a) 2 min
(b) 4 min
(c) 6 min
(d) 8 min