Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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11.

What is the effect of increasing pressure on the dissociation of PCl5 according to the equation?

PCl5 (g)  PCl3 (g) + Cl(g)

  • Dissociation decreases

  • Dissociation increases

  • Dissociation does not change

  • None of the above


A.

Dissociation decreases

According to Le-Chatelier principle the reactions in which member of moles are increasing in forward reaction are favoured at low pressure or high volume.

PCl5 (g)  PCl3 (g) + Cl2 (g)

Since, number of moles are increasing in the forward reaction in above reaction.

 Reaction is favoured at low pressure. At high pressure, rate of dissociation of PCl5 decreases.


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12.

The ground state term symbol for an electronic state is governed by :

  • Heisenberg's principle

  • Hund's rule

  • Aufbau principle

  • Pauli exclusion principle


13.

The following salt shows maximum covalent character:

  • AlCl3

  • MgCl2

  • CsCl

  • LaCl3


14.

Which of the following is paramagnetic ?

  • B2

  • C2

  • N2

  • F2


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15.

What is the ratio of mass of an electron to the mass of a proton ?

  • 1 : 2

  • 1 : 1

  • 1 : 1837

  • 1 : 3


16.

Pauling's electronegativity values for elements are useful in predicting :

  • polarity of bonds in molecules

  • position of elements in electromotive series

  • co-ordination number

  • dipole moment of various molecules


17.

The trigonal bipyramidal geometry results from the hybridisation :

  • dsp3 or sp3d

  • dsp2 or sp2d

  • d2sp3 or sp3d2

  • d3p2 or d2p3


18.

Two moles of PCl5 were heated in a closed vessel of 2 L. At equilibrium, 40% of PCl5 is dissociated into PCl3 and Cl3. The value of equilibrium constant is :

  • 0.53

  • 0.267

  • 2.63

  • 5.3


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19.

The molecule having smallest bond angle is :

  • H2O

  • H2S

  • NH3

  • H2Te


20.

What is the effect of having the pressure by doubling the volume on the following system at 500°C?

H2 (g) + I2 (g)  2HI (g)

  • Shift to reactant side

  • Shift to product formation

  • Liquefaction of HI

  • No effect


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