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GS
GS Set-1
Chemistry
Physical Chemistry
238

Physical Chemistry MCQ with Answers

238) Value of pK_a for acetic acid at 25^oC is 4.75. What will be the pH value of the solution in which ratio of concentration of sodium acetate and acetic acid is 10?

3.75

4.75

5.75

Answer is:

5.75

Explanation:

pH = pK_a + log([salt]⁄[acid])

Physical Chemistry MCQ with Answers

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239) Phenolphthalein gives which of the following colours in acidic medium?

Pink

Red

No colour

Violet

Answer is:

No colour

Explanation:

Colourless in acidic medium because concentration of pH is low.

240) If pK_{a_{of acetic acid at 25^oC is 4.75, then determine the pH of that solution in which 0.02M sodium acetate and acetic acid are present:}}

4.75

3.75

5.75

2.75

Answer is:

4.75

Explanation:

[salt] = [acid]

241) When equal volumes of the solutions are mixed, precipitation of AgCl (K_sp = 1.8 x 10⁻¹¹) will occur with:

10⁻⁴M Ag⁺ + 10⁻⁴M Cl⁻

10⁻⁵M Ag⁺ + 10⁻⁵M Cl⁻

10⁻⁶M Ag⁺ + 10⁻⁶M Cl⁻

10⁻¹⁰M Ag⁺ + 10⁻¹⁰M Cl⁻

Answer is:

10⁻⁴M Ag⁺ + 10⁻⁴M Cl⁻

Explanation:

Precipitation occurs when ionic product > solubility product.

242) pK_a values of two acids A and B are 4 and 5. The strengths of these two acids are related as:

Strength of acid A : Strength of acid B = 4 : 5

Acid A is about 3 times stronger than acid B

Acid B is 10 times stronger than acid A

The strengths of the two acids cannot be compared

Answer is:

Acid A is about 3 times stronger than acid B

Physical Chemistry MCQ with Answers

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238) Value of pKa for acetic acid at 25oC is 4.75. What will be the pH value of the solution in which ratio of concentration of sodium acetate and acetic acid is 10?

5.75

Physical Chemistry MCQ with Answers

Related Physical Chemistry MCQ with Answers

239) Phenolphthalein gives which of the following colours in acidic medium?

No colour

240) If pKa of acetic acid at 25oC is 4.75, then determine the pH of that solution in which 0.02M sodium acetate and acetic acid are present:

4.75

241) When equal volumes of the solutions are mixed, precipitation of AgCl (Ksp = 1.8 x 10−11) will occur with:

10−4M Ag+ + 10−4M Cl−

242) pKa values of two acids A and B are 4 and 5. The strengths of these two acids are related as:

Acid A is about 3 times stronger than acid B

Physical Chemistry MCQ with Answers

238) Value of pK_a for acetic acid at 25^oC is 4.75. What will be the pH value of the solution in which ratio of concentration of sodium acetate and acetic acid is 10?

240) If pK_{a_{of acetic acid at 25^oC is 4.75, then determine the pH of that solution in which 0.02M sodium acetate and acetic acid are present:}}

241) When equal volumes of the solutions are mixed, precipitation of AgCl (K_sp = 1.8 x 10⁻¹¹) will occur with:

10⁻⁴M Ag⁺ + 10⁻⁴M Cl⁻

242) pK_a values of two acids A and B are 4 and 5. The strengths of these two acids are related as: