Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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11.

The correct order of decreasing length of the bond as indicated by the arrow in the following structures is

       

  • I >II > III

  • II > I > III

  • III > II > I

  • I > III > II


C.

III > II > I

The length of carbon-carbon single bond is always greater than that of the carbon-carbon double bond.
In III, positive charge is not in conjugation of double bond, so the bond does not acquire a double bond character. However, chances of acquiring double bond character (of the indicated bond) is much more in I than that in case of II.

Thus, the correct order of decreasing bond lenght is

         


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12.

An atomic nucleus having low n/p ratio tries to find stability by

  • the emission of an α-particle

  • the emission of a positron

  • capturing an orbital electron (K-electron capture)

  • emission of a β-particle


13.

( G7632, Se7634) and ( Si3014, S3216) are example of 

  • isotopes and isobars

  • isobars and isotones

  • isotones and isotopes

  • isobars and isotopes


14.

98Cf246  was formed along with a neutron when an unknown radioactive substance was bombarded with 6C12. The unknown substance was 

  • 91Pa234

  • 90Th234

  • 92U235

  • 92U238


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15.

The values of H and S of a certain reaction are -400 kJ mol-1 and -20 kJ mol-1K-1 respectively. The temperature below which the reaction is spontaneous, is

  • 100 K

  • 20°C

  • 20 K

  • 120°C


16.

The correct statement regarding the following energy diagrams is

        

  • Reaction M is faster and less exothermic than reaction N

  • Reaction M is slower and less exothermic than reaction N

  • Reaction M is faster and more exothermic than reaction N

  • Reaction M is slower and more exothermic than reaction N


17.

Commercial sample of H2O2 is labeled as 10 V. Its % strength is nearly

  • 3

  • 6

  • 9

  • 12


18.

The enthalpy of vaporisation of a certain liquid at its boiling point of 35°C is 24.64 kJ mol-1. The value of change in entropy for the process is

  • 704 JK -1mol-1

  • 80 JK -1mol-1

  • 24.64 JK -1mol-1

  • 7.04 JK-1mol-1


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19.

Given that

C + O2  CO2; H°= -x kJ2CO + O2 2CO2; H°= -y kJ

The heat of formation of carbon monoxide will be

  • y- 2x2

  • y + 2x

  • 2x - y 

  • 2x-y2


20.

In case of heteronuclear diatomics of the type AB, where A is more electronegative than B, bonding molecular orbital resembles the character of A more than that of B. The statement

  • is false

  • is true

  • cannot be evaluated since data is not sufficient

  • is true only for certain systems


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