16) Permanent hardness of water may be removed by the addition of
A. sodium carbonate
B. alum
C. potassium permanganate
D. lime
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Answer Option A
17) The most important ore of aluminium is
A. galena
B. calamine
C. calcite
D. bauxite
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Answer Option D
18) Which of the following was to be discovered first in the chromospheres of the sun?
A. Krypton
B. Xenon
C. Neon
D. Helium
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Answer Option D
19) Sodium metal is kept under
A. petrol
B. alcohol
C. water
D. kerosene
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Answer Option D
20) From which mineral is radium obtained?
A. Rutile
B. Haematite
C. Limestone
D. Pitchblende
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Answer Option D
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