JEE Main 2017 · 2 Apr · Shift 1 · Chemistry Q40

ChemistrySingle correct+4 / -1Question 40 of 90

p $K_a$ of a weak acid (HA) and p $K_b$ of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is :

7.0

1.0

7.2

6.9

Answer and worked solution

Official answer: D

For a salt of a weak acid and a weak base,
$\text{pH}=7+\tfrac12(pK_a-pK_b)=7+\tfrac12(3.2-3.4)=6.9.$

JEE Main 2017 · 2 Apr · Shift 1, Chemistry question 40