Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

pH value of which one of the following is not equal to one?

  • 0.1 M HNO3

  • 0.05 M H2SO4

  • 0.1 M CH3COOH

  • 50 cm3 of 0.4 M HCl + 50 cm3of 0.2 M NaOH


22.

Which one of these is not true for benzene?

  • It forms only one type of monosubstituted product

  • There are three carbon-carbon single bonds and three carbon-carbon double bonds

  • The heat of hydrogenation of benzene is less than the theoretical value

  • The bond angle between the carbon-carbon bonds is 120°


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23.

Generally, the first ionization energy increases along a period. But there are some exceptions. One which is not an exception is

  • N and O

  • Na and Mg

  • Mg and Al

  • Be and B


B.

Na and Mg

Na belongs to IA group and Mg belongs to IIA group. On moving form left to right in a period, first ionization energy increases, thus, IE of Mg is greater than the IE of Na.
                                   IE order Mg> Na


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24.

Which one of the following conformations of cyclohexane is the least stable?

  • Half-chair

  • Boat

  • Twisted-boat

  • Chair


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25.

Which one of the following is a molecular crystal?

  • Rock salt

  • Quartz

  • Dry ice

  • Diamond


26.

Chloroacetic acid is a stronger acid than acetic acid. This can be explained using

  • -M effect

  • - I effect

  • +M effect

  • +I effect


27.

For alkali metals, which one of the following trends is incorrect?

  • Hydration energy : Li > Na > K > Rb

  • Ionization energy : Li > Na > K > Rb

  • Density : Li < Na < K < Rb

  • Atomic size : Li < Na < K < Rb


28.

A dibromo derivative of an alkane reacts with sodium metal to form an alicyclic hydrocarbon. The derivative is

  • 1, 1-dibromopropane

  • 2, 2-dibromobutane

  • 1, 2-dibromoethane

  • 1, 4-dibromobutane


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29.

In the electrolytic refining of zinc

  • graphite is at the anode

  • the impure metal is at the cathode

  • the metal ion get reduced at the anode

  • acidified zinc sulphate is the electrolyte


30.

In chromite ore, the oxidation number of iron, and chromium are respectively

  • +3,+2

  • +3,+6

  • +2,+6

  • +2,+3


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