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GS
GS Set-1
Chemistry
Physical Chemistry
242

Physical Chemistry MCQ with Answers

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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243) A buffer solution has equal volumes of 0.2M NH₄OH and 0.02M NH₄Cl. The pK_b of the base is 5. The pH is:

Answer is:

10

Explanation:

pOH = pK_b + log ([salt]⁄[base])

244) The number of OH⁻ ions in 1 mL of solution having pH = 4 is:

10⁻⁴

10⁻¹⁰

6.02 x 10¹⁰

6.02 x 10¹³

Answer is:

6.02 x 10¹⁰

Explanation:

[H⁺] [OH⁻] = 10⁻¹⁴

245) For preparing a buffer solution of pH 6 by mixing sodium acetate and acetic acid, the ratio of the concentration of salt and acid should be: (K^a = 10⁻⁵)

1:10

10:01

100:01:00

0.111111111

Answer is:

0.417361111

Explanation:

pH = pK_a + log([salt]⁄[acid])

246) 0.15 mol of pyridinium chloride has added to 500 cc of 0.2M pyridine solution (K_b for pyridine is 1.5 x 10⁻⁹M). pH is:

Answer is:

5

Explanation:

pOH = pK_b + log ([salt]⁄[base])

Physical Chemistry MCQ with Answers

For more MCQ's Click Here

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

Related Physical Chemistry MCQ with Answers

243) A buffer solution has equal volumes of 0.2M NH4OH and 0.02M NH4Cl. The pKb of the base is 5. The pH is:

10

244) The number of OH− ions in 1 mL of solution having pH = 4 is:

6.02 x 1010

245) For preparing a buffer solution of pH 6 by mixing sodium acetate and acetic acid, the ratio of the concentration of salt and acid should be: (Ka = 10−5)

0.417361111

246) 0.15 mol of pyridinium chloride has added to 500 cc of 0.2M pyridine solution (Kb for pyridine is 1.5 x 10−9M). pH is:

5

Physical Chemistry MCQ with Answers

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

243) A buffer solution has equal volumes of 0.2M NH₄OH and 0.02M NH₄Cl. The pK_b of the base is 5. The pH is:

244) The number of OH⁻ ions in 1 mL of solution having pH = 4 is:

6.02 x 10¹⁰

245) For preparing a buffer solution of pH 6 by mixing sodium acetate and acetic acid, the ratio of the concentration of salt and acid should be: (K^a = 10⁻⁵)

246) 0.15 mol of pyridinium chloride has added to 500 cc of 0.2M pyridine solution (K_b for pyridine is 1.5 x 10⁻⁹M). pH is: