31) Which one of the following raw material is used in the manufacture of foam used in mattresses, cushions, etc?
32) Permanent magnets can be made from:
33) Atmospheric pressure exerted on the earth is due to the:
(A) Rotation of the earth
(B) Revolution of the earth
(C) Gravitational pull
(D) Uneven heating of the earth
34) Quantity of fresh air required for a man is:
(A) 1000 cubic feet of air for every 20 minutes
(B) 1000 cubic feet of air for every 20 seconds
(C) 1000 cubic feet of air for every 10 minutes
(D) 1000 cubic feet of air for every 10 seconds
35) Where does the oxygen that keeps us alive come from?
(A) Carbon dioxide
(B) Carbonates absorbed from soil
(C) Oxides of minerals
36) Which one of the following metals pollutes the air of a city having large number of automobiles?
37) The snow on the mountains does not melt all at once when it is heated by the sun because
(A) It becomes very hard
(B) It reflects most of the heat from the sun
(C) It has a low specific heat capacity
(D) It has a high latent heat of fusion
38) Where is blood formed in the human body?
(C) Bone marrow
39) Which of the following is the name of the smallest part of the matter discovered by the scientists?
40) Trachoma is a disease of the: