Ans: (c)
20. Which of the following is not an isotope of hydrogen?
    (a) protium
    (b) deuterium
    (c) iterium
    (d) tritium
Ans: (c)
21. 8O16, 8O17, 8O18, are called : [BPSC (ASI) 2002]
    (a) isotopes
    (b) isotones
    (c) isobars
    (d) isoneutrons
Ans: (a)
22. The radioactive isotope of hydrogen is called:
    (a) duterium
    (b) protium
    (c) radium
    (d) tritium
Ans: (d)
23. Carbon dioxide is called a greenhouse gas because- [CDS 2012]
    (a) Its concentration remains always higher than other gases
    (b) It is used in photosynthesis
    (c) It absorbs infrared radiation
    (d) It emits visible radiation
Ans: (c)
24. In a dry cell, which of the following are used as electrolytes? [JPSC (Pre) 2011]
    (a) Ammonium chloride and zinc chloride
    (b) Ammonium chloride and calcium chloride
    (c) Magnesium chloride and zinc chloride
    (d) Sodium chloride and zinc chloride
Ans: (a)
25. The iso electronic of Al+3 is : [CDS2001]
    (a) Cl -
    (b) Al
    (c) S - -
    (d) F -
Ans: (d)
26. Which is the second most abundant metal in the earth"s crust? [JPSC (Pre) 2011]
    (a) Iron
    (b) Aluminium
    (c) Copper
    (d) Zinc
Ans: (a)
27. Age of fossil may be found out by determining the ratio of two isotopes of carbon. The isotopes are- [CDS 2012]
    (a) C-12 and C-13
    (b) C-12 and Carbon block
    (c) C-12 and C-14
    (d) C-13 and C-14
Ans: (c)
28. Teflon is a / an [JPSC (Pre) 2011]
    (a) fluorocarbon
    (b) hydro carbon
    (c) pesticide
    (d) insecticide
Ans: (a)
29. The shape of ethylene molecule is :
    (a) linear
    (b) tetrahedral
    (c) coplanar triangular
    (d) hectohedral
Ans: (c)