JEE Main · 2020 · Shift-ImediumIEQ-036

Arrange the following solutions in the decreasing order of pOH: (A) 0.01 M HCl (B) 0.01 M NaOH (C) 0.01 M CH3COONa (D)…

Ionic Equilibrium · Class 11 · JEE Main Previous Year Question

Question

Arrange the following solutions in the decreasing order of pOH:

(A) 0.01 M HCl (B) 0.01 M NaOH (C) 0.01 M CH3COONa\mathrm{CH_3COONa} (D) 0.01 M NaCl

Options
  1. a

    (A) > (C) > (D) > (B)

  2. b

    (A) > (D) > (C) > (B)

  3. c

    (B) > (C) > (D) > (A)

  4. d

    (B) > (D) > (C) > (A)

Correct Answerb

(A) > (D) > (C) > (B)

Detailed Solution

pOH = 14 − pH. Higher pOH = lower pH = more acidic.

Step 1 — Determine pH of each:

(A) 0.01 M HCl: Strong acid, pH = 2 \rightarrow pOH = 12 (highest pOH)

(B) 0.01 M NaOH: Strong base, pH = 12 \rightarrow pOH = 2 (lowest pOH)

(C) 0.01 M CH3COONa\mathrm{CH_3COONa}: Salt of weak acid + strong base \rightarrow basic, pH ≈ 8.4 \rightarrow pOH ≈ 5.6

(D) 0.01 M NaCl: Neutral salt, pH = 7 \rightarrow pOH = 7

Step 2 — Decreasing order of pOH: pOH:A(12)>D(7)>C(5.6)>B(2)\mathrm{pOH}: A(12) > D(7) > C(5.6) > B(2)

Answer: Option (2) — (A) > (D) > (C) > (B)

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Arrange the following solutions in the decreasing order of pOH: (A) 0.01 M HCl (B) 0.01 M NaOH (C)… (JEE Main 2020) | Canvas Classes