JEE Main 2017 · 9 Apr · Shift 1 · Chemistry Q32

ChemistrySingle correct+4 / -1Question 32 of 90

50 mL of 0.2 M ammonia solution is treated with 25 mL of 0.2 M HCl. If $pK_b$ of ammonia solution is 4.75, the pH of the mixture will be :

3.75

4.75

8.25

9.25

Answer and worked solution

Official answer: D

10 mmol $\ce{NH3}$ and 5 mmol HCl give 5 mmol $\ce{NH4+}$ and 5 mmol $\ce{NH3}$ left: a buffer with pOH = $pK_b$ = 4.75. So pH = 9.25.

JEE Main 2017 · 9 Apr · Shift 1, Chemistry question 32