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Friday, 9 October

NEET UG 2025 · Chemistry · Question 59

NEET 2025 Chemistry, question 59

Question 59 of the NEET 2025 paper (code 45) is a Chemistry question from Equilibrium. Its idea, pH of Polyprotic Acids, was asked only this once in NEET 2017–2026. The NTA final answer key gives option 4.

Updated 2026-10-08

Q59 · Chemistry

Phosphoric acid ionizes in three steps with their ionization constant values Ka1K_{a_1}, Ka2K_{a_2} and Ka3K_{a_3}, respectively, while K is the overall ionization constant. Which of the following statements are true?

A. log⁡K=log⁡Ka1+log⁡Ka2+log⁡Ka3\log K = \log K_{a_1} + \log K_{a_2} + \log K_{a_3}

B. H3PO4H_3PO_4 is a stronger acid than H2PO4−H_2PO_4^- and HPO42−HPO_4^{2-}.

C. Ka1>Ka2>Ka3K_{a_1} > K_{a_2} > K_{a_3}

D. Ka1=Ka3+Ka22K_{a_1} = \frac{K_{a_3} + K_{a_2}}{2}

Choose the correct answer from the options given below:

  1. 1A and B only
  2. 2A and C only
  3. 3B, C and D only
  4. 4A, B and C onlyOfficial answer

Official answer: option 4 · NTA final answer key

Same idea

The only question on pH of Polyprotic Acids

No other NEET paper from 2017–2026 tested this exact idea.

pH of Polyprotic Acids: every question and how it was framed

The chapter

Equilibrium in ten years of NEET

26 questions from 2017–2026, asked in 10 of 10 papers, about 2.5 a paper. pH and Buffer Solutions alone had 13.

Equilibrium: questions per paper

0363’173’183’192’201’212’222’235’244’251’26