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Saturday, 31 October

JEE Main 2021 · MathsMultiple choiceSingle correctEasyConceptual

JEE Main 22 July 2021, Shift 2, Maths Q66

Question 66 of 90 in this shift, Maths question 6 of 30, Section A.

Which of the following Boolean expressions is not a tautology ?
  1. (1)(p⇒q)∨(∼q⇒p)(\mathrm{p}\Rightarrow\mathrm{q})\vee(\sim\mathrm{q}\Rightarrow\mathrm{p})
  2. (2)(p⇒∼q)∨(∼q⇒p)(\mathrm{p}\Rightarrow\sim\mathrm{q})\vee(\sim\mathrm{q}\Rightarrow\mathrm{p})
  3. (3)(∼p⇒q)∨(∼q⇒p)(\sim\mathrm{p}\Rightarrow\mathrm{q})\vee(\sim\mathrm{q}\Rightarrow\mathrm{p})Official answer
  4. (4)(q⇒p)∨(∼q⇒p)(\mathrm{q}\Rightarrow\mathrm{p})\vee(\sim\mathrm{q}\Rightarrow\mathrm{p})

Official answer

Option 3

NTA final key.

Chapter
Mathematical Reasoning
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.