In which of the following mixed aqueous solutions, pH =pKa a

Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

Advertisement

41.

In which of the following mixed aqueous solutions, pH =pKat equilibrium?

(1) 100 mL of 0.1 M CH3COOH +100mL 0.1 M CH3COONa.

(2) 100 mL of 0.1 M CH3COOH  + 50 mL of 0.1 M NaOH.

(3) 100 mL of 0.1 M CH3COOH + 100 mL of 0.1 M NaOH.

(4) 100 mL of 0.1 M CH3COOH + 100 mL of 0.1 M NH3.

  • (1) is correct

  • (2) is correct

  • (3) is correct

  • Both (1) and (2) are correct


A.

(1) is correct

B.

(2) is correct

D.

Both (1) and (2) are correct

pH of buffer solutions is given by    pH = pKa+ log saltacid(1) CH3COOH                  and          CH3COONa     100 ×0.1                                       100 ×0.1     No. of milimoles = 10                  = 10 ·: [salt]= [acid]= 10, pH= pKa+ log 1010    pH=pKa(2)       CH3COOH 100 × 0.1+ NaOH50 ×0.1 CH3COONa + H2OInitial = 10                    5                 0                  0 Final =5                       0                 5                  0[salt] = [acid]= 5, pH = pKa+ log55    therefore pH=pKa(3) CH3COOH 100 × 0.1+ NaOH50 ×0.1 CH3COONa + H2OInitial = 10            10                0                  0 Final =  0              0                 10               10[salt] = 10 and [acid] =0 pH = pKa+ log 100  therefore pH= pKa(4)      CH3COOH + NH3 CH3COONH4Initial =   10             10No buffer action Final due to weak CH3COONH4  salt           pHpKa 


Advertisement
42.

Consider the following salts : NaCl, HgCl2, Hg2Cl2, CuCl2, CuCl and AgCl.

Identify the correct set of insoluble salts in water.

  • Hg2Cl2, CuCl, AgCl

  • HgCl2, CuCl, AgCl

  • Hg2Cl2, CuCl2, AgCl

  • Hg2Cl2, CuCl, NaCl


43.

The ratio of volumes of CH3COOH 0.1 N to CH3COONa 0.1 N required to prepare a buffer solution of pH 5.74 is (Given, pKa of CH3COOH is 4.74)

  • 10 : 1

  • 5 : 1

  • 1 : 5

  • 1 : 10


44.

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


Advertisement
45.

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


46.

At 25°C, the solubility product of salt of MX2 type is 3.2 × 10-8 in water. The solubility (in mol/L) of MX2 in water at the same temperature will be

  • 1.2 × 10-3

  • 2 × 10-3

  • 3.2 × 10-3

  • 1.75 × 10-3


47.

The different colours of litmus in acidic, neutral and basic solutions are, respectively.

  • red, orange and blue

  • blue, violet and red

  • red, colourless and blue

  • red, violet and blue


48.

The correct order of equivalent conductances at infinite dilution in water at room temperature for H+, K+, CH3COO- and HO- ions is

  • HO- > H+ > K+ > CH3COO-

  • H+ > HO- > K+ > CH3COO-

  • H+ > K+ > HO- > CH3COO-

  • H+ > K+ > CH3COO- > HO-


Advertisement
49.

The pH of 10-4 M KOH solution will be

  • 4

  • 11

  • 10.5

  • 10


50.

For a chemical reaction at 27°C, the activation energy is 600 R. The ratio of the rate constants at 327°C to that of at 27°C will be

  • 2

  • 40

  • e

  • e2


Advertisement