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Saturday, 31 October

JEE Main 2020 · ChemistryMultiple choiceAssertion–reasonMediumConceptual

JEE Main 8 January 2020, Shift 2, Chemistry Q28

Question 28 of 75 in this shift, Chemistry question 3 of 25, Section A.

For the following Assertion and Reason, the correct option is : Assertion : The pH of water increases with increase in temperature. Reason : The dissociation of water into H+\mathrm{H^+} and OH−\mathrm{OH^-} is an exothermic reaction.
  1. (1)Both assertion and reason are true, and the reason is the correct explanation for the assertion.
  2. (2)Both assertion and reason are true, but the reason is not the correct explanation for the assertion.
  3. (3)Assertion is not true, but reason is true.
  4. (4)Both assertion and reason are false.Official answer

Official answer

Option 4

NTA final key (Jan 2020).

Chapter
Equilibrium
Topic
pH and Buffers
Idea tested
Temperature Dependence of Kw and Neutral pH

Same topic in other shifts

All pH and Buffers questions
  1. 2 Apr 2026, Shift 2 · Q52The first and second ionization constants of a weak dibasic acid H2A\mathrm{H_2A} are 8.1×10−88.1 \times 10^{-8} and 1.0×10−131.0 \times 10^{-13}…HardSingle correct
  2. 2 Apr 2026, Shift 2 · Q56At 25°C, 20.0 mL of 0.2 M weak monoprotic acid HX is titrated against 0.2 M NaOH. The pH of the solution (a) at the start of the titration…MediumSingle correct
  3. 4 Apr 2026, Shift 1 · Q74The pH of a solution obtained by mixing 55 mL of 0.10.1 M NH4OH\mathrm{NH_4OH} solution with 250250 mL of 0.10.1 M NH4Cl\mathrm{NH_4Cl} solution…MediumNumerical value
  4. 4 Apr 2026, Shift 2 · Q5520 mL of a solution of acetic acid required 28.4 mL of 0.1 M NaOH for its neutralization. A solution (X) was prepared by mixing 20 mL of…EasySingle correct
  5. 5 Apr 2026, Shift 1 · Q56Arrange the following resultant mixtures in increasing order of their pH values A. 10 mL 0.2 M Ca(OH)2\mathrm{Ca(OH)_2} + 25 mL 0.1 M HCl B. 10…MediumOther
  6. 6 Apr 2026, Shift 2 · Q56Given is a concentrated solution of a weak electrolyte AxBy\mathrm{A_xB_y} of concentration 'c' and dissociation constant 'K'. The degree of…HardSingle 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.