JEE Main 2021 · ChemistryNumerical answerNumerical valueMediumCalculation

JEE Main 26 August 2021, Shift 1, Chemistry Q55

Question 55 of 90 in this shift, Chemistry question 25 of 30, Section B.

The

\mathrm{OH^-}

concentration in a mixture of 5.0 mL of 0.0504 M

\mathrm{NH_4Cl}

and 2 mL of 0.0210 M

\mathrm{NH_3}

solution is

x \times 10^{-6}

M. The value of

x

is __________. (Nearest integer) [Given

\mathrm{K_w} = 1 \times 10^{-14}

and

\mathrm{K_b} = 1.8 \times 10^{-5}

]

Official answer

NTA final key.

Chapter: Equilibrium
Topic: pH and Buffers
Idea tested: Basic Buffer pH Calculation

Same idea in other shifts

Asked 3× in all

4 Apr 2026, Shift 1 · Q74The pH of a solution obtained by mixing $5$ mL of $0.1$ M $\mathrm{NH_4OH}$ solution with $250$ mL of $0.1$ M $\mathrm{NH_4Cl}$ solution…MediumNumerical value
26 Jul 2022, Shift 2 · Q63Class XII students were asked to prepare one litre of buffer solution of pH 8.26 by their Chemistry teacher. The amount of ammonium…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.