Ans: (b)
10. Table salt (NaCl) is a product of : [BPSC (Pre) 2011]
    (a) weak acid and weak base
    (b) weak acid and strong base
    (c) strong acid and strong base
    (d) strong acid and weak base
Ans: (b)
11. Which of the following is not a radioactive element? [IAS (Pre) 2001]
    (a) astetin
    (b) franscium
    (c) titenium
    (d) zcronium
Ans: (d)
12. Artificial silk is also called: [JPSC (Pre) 2011]
    (a) rayon
    (b) dacron
    (c) fibre glass
    (d) nylon
Ans: (a)
13. The elements of a group in the periodic table [CDS 2012]
    (a) have similar chemical properties
    (b) have consecutive atomic numbers
    (c) are isobars
    (d) are isotopes
Ans: (a)
14. The half-life of a radioactive substance is 4 months then the time spent in decaying 1⁄4 th of the substance would
         be : [IAS (Pre) 2001]
    (a) 3 months
    (b) 4 months
    (c) 8 months
    (d) 12 months
Ans: (c)
15. The estimation of the age of the earth is done by :
    (a) uranium dating
    (b) carbon dating
    (c) atomic clock
    (d) bio clock
Ans: (a)
16. In the isotope of an atomic nucleus: [BPSC 1996]
    (a) number of neutrons are same but number of protons are different
    (b) number of protons are same but number of neutrons are different
    (c) both number of protons and neutrons are same
    (d) both number of protons and neutrons are different
Ans: (b)
17. Cooking gas is a mixture of: [JPSC (Pre) 2011]
    (a) carbon monoxide and carbon dioxide
    (b) butane and propane
    (c) methane and ethylene
    (d) carbondioxide and oxygen
Ans: (b)
18. The pH of fresh ground water slightly decreases upon exposure to air because- [CDS 2012]
    (a) Carbon dioxide from air is dissolved in the water
    (b) Oxygen from air is dissolved in the water
    (c) The dissolved carbon dioxide of the ground water escapes into air
    (d) The dissolved oxygen of the ground water escapes into the air
Ans: (a)
19. Cobalt-60 is commonly used in radiation therapy, because it emits: [JPSC (Pre) 2011]
    (a) alpha rays
    (b) beta rays
    (c) gamma rays
    (d) X-rays
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