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 Multiple Choice QuestionsMultiple Choice Questions

671.

A solution with pH = 2 is more acidic than one with a pH =6, by a factor of

  • 4000

  • 5000

  • 8000

  • 10,000


672.

Within the list shown below, the correct pair of structures of alanine in pH ranges 2-4 and 9-11 is

I. H3N+-CH(CH3)CO2H
II. H2N-CH(CH3)CO2-
III. H3N+-CH(CH3)CO2-
IV.H2N-CH(CH3)CO2H

  • I and II

  • I and III

  • II and III

  • III and IV


673.

Assertion: Relative strength of acids can be known by knowing the value of dissociation constant.

Reason : It gives the value of H dissolved in solution.

  • If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

  • If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

  • If Assertion is true but Reason is false.

  • If Assertion is false but Reason is true.


674.

A 100 mL 0.1 = (M) solution of ammonium acetate is diluted by adding 100 mL of water. The pH of the resulting solution will be (pKa of acetic acid is nearly equal to pKb of NH4OH).

  • 4.9

  • 5.0

  • 7.0

  • 10.0


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675.

In a reversible chemical reaction at equilibrium, if the concentration of any one of the reactants is doubled, then the equilibrium constant will:

  • also be doubled

  • be halved

  • remains the same

  • becomes one-fourth


676.

The equivalent weight of K2Cr2O7 in acidic medium is expressed in terms of its molecular weight (M) as:

  • M/3

  • M/4

  • M/6

  • M/7


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677.

20 mL 0.1 (N) acetic acid is mixed with 10 ml  0.l(N) solution of NaOH. The pH of the resulting solution is (pKb of acetic acid is 4.74)

  • 3.74

  • 4.74

  • 5.74

  • 6.74


B.

4.74

CH3CHO         +    NaOH

initial 20x0.1       =10x0.1

=2mmol             =1mmol

at time t             =(1-1)

=(2-1)                =0 mmol

=1mmol

 CH3COONa1 mmol + H2O

From Henderson's equation,

pH =pKa + log[CH3COONa][CH3COOH]

=4.74 + log11

=4.74


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678.

The pH of 10-4M KOH solution will be

  • 4

  • 11

  • 10.5

  • 10


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679.

The pH of an aqueous solution of CH3COONa of concentration C(M) is given by:

  • 7 - 1/2 pKa - 1/2 log C

  • 1/2 pKw + 1/2 pKb + 1/2 log C

  • 1/2 pKw - 1/2 pKb - 1/2 log C

  • 1/2 pKw - pKa + 1/2 log C


680.

If the equilibrium constants of the following equilibria,

SO2 + 1/2O2  SO3 and 2SO3  2SO2 + O2

are given by K1 and K2 respectively, which of the following relations is correct?

  • K2 = (1/K1)2

  • K1 = (1/K3)3

  • K2 = (1/K1)

  • K2 = (K1)2


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