Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Identify the correct statement for the change of Gibbs energy for a system (ΔGsystem) at constant temperature and pressure

  • If ΔGsystem > 0, the process is spontaneous

  • If ΔGsystem =0, the system has attained equilibrium

  • If ΔGsystem < 0, the system is still moving in a particular direction

  • If ΔGsystem < 0, the system is still moving in a particular direction

3284 Views

2.

Assume each reaction is carried out in an open container. For which reaction will ΔH = ΔE?

  • H2 (g) + Br2 (g) →2HBr (g)

  • C (s) + 2 H2O (g) → 2 H2 (g) + CO2 (g)

  • PCl5 (g) →PCl3 (g) + Cl2 (g) 

  • PCl5 (g) →PCl3 (g) + Cl2 (g) 

835 Views

3.

Given: The mass of electron is 9.11 x 10-31 kg
Planck constant is 6.626 x 10-34 Js,
the uncertainty involved in the measurement of velocity within a distance of 0.1 A is:

  • 5.79 x 106 ms-1

  • 5.79 x 107 ms-1

  • 5.79 x 108 ms-1

  • 5.79 x 108 ms-1

784 Views

4.

The enthalpy and entropy change for the reaction:

Br2 (l) + Cl2 (g)→ 2BrCl (g)

are 30 kJ mol-1 and 105 JK-1 mol-1 respectively. The temperature at which the reaction will be in equilibrium is:

  • 285.7 K 

  • 273 K

  • 450 K

  • 450 K

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5.

For the reaction,

CH4  (g) + 2 O2 (g) ⇌ CO2 (g) + 2H2O (l), 

ΔrH = - 170. 8 kJ mol-1

Which of the following statements is not true? 

  • At equilibrium, the concentrations of CO2 (g) and H2O (l) are not equal

  • The equilibrium constant for the reaction is given by Kpfraction numerator left square bracket CO subscript 2 right square bracket over denominator left square bracket CH subscript 4 right square bracket left square bracket straight O subscript 2 right square bracket end fraction

  • Addition of CH4 (g) or O2 (g) at equilibrium will cause a shift to the right

  • Addition of CH4 (g) or O2 (g) at equilibrium will cause a shift to the right


B.

The equilibrium constant for the reaction is given by Kpfraction numerator left square bracket CO subscript 2 right square bracket over denominator left square bracket CH subscript 4 right square bracket left square bracket straight O subscript 2 right square bracket end fraction

For the reaction,

CH4  (g) + 2 O2 (g) ⇌ CO2 (g) + 2H2O (l), 

ΔrH = - 170. 8 kJ mol-1

This equilibrium is an example of heterogeneous chemical equilibrium.Hence, for it


not correct expression.
In addition of CH4 (g) or O2 (g) at equilibrium Kc = will be decreased according to expression (i) but Kc remains constant at constant  at constant temperature fro a reaction, so for maintaining the constant value of Kc, the concentration of CO2 will increase in same order. Hence, on the addition of CH4 or O2 equilibrium will cause to the right.

This reaction is an example of an exothermic reaction.

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6.

The enthalpy of combustion of H2, cyclohexene (C6H10) and cyclohexene (C6H12) are -241, -3800 and -3920 kJ per mol respectively.The heat of hydrogenation of cyclohexane is:

  • -212 kJ mol

  • +121 kJ mol

  • +242 kJ per mol

  • +242 kJ per mol

1278 Views

7.

Which of the following pairs consitutes a buffer?

  • HNO2 and NaNO2

  • NaOH and NaCl

  • HNO3 and NH4NO3

  • HNO3 and NH4NO3

632 Views

8.

The hydrogen ion concentration of a 10-8 M HCL aqueous solution at 298 K (Kw = 10-14) is:

  • 1.0 x 10-6

  • 1.0525 x 10-7 M

  • 9.525 x 10-8 M

  • 9.525 x 10-8 M

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9.

In which of the following molecules are all the bonds not equal? 

  • ClF3

  • BF3

  • AlF3

  • AlF3

1107 Views

10.

The orientation of an atomic orbital is governed by:

  • azimuthal quantum number

  • spin quantum number

  • magnetic quantum number

  • magnetic quantum number

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