Which of the following pairs consitutes a buffer? from Chemistr

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

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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) 

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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

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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

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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

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7.

Which of the following pairs consitutes a buffer?

  • HNO2 and NaNO2

  • NaOH and NaCl

  • HNO3 and NH4NO3

  • HNO3 and NH4NO3


A.

HNO2 and NaNO2

A pair constituent with an HNO2 and NaNO2 because HNO2 is weak acid and NaNO2 is a salt of the weak acid (HNO2) with a strong base (NaOH). Hence, it is an example of acidic buffer solution.

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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

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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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