Let the operations *, ⊙ ∈{∧,∨}. If (p∗q)⊙(p⊙∼q) is a tautology, then the ordered pair ( ∗,⊙ ) is :
(A)(∨,∧)
(B)(∨,∨)✓ Correct
(C)(∧,∧)
(D)(∧,∨)
Answer: (B)
Solution
We check each option. For option (A) with ∗=∨,⊙=∧: (p∨q)∧(p∨∼q)≡p∨(q∧∼q)≡p, which is not a tautology. For option (B) with ∗=∨,⊙=∨: (p∨q)∨(p∨∼q). This is always true because for any truth values of p and q, at least one of q or ∼q is true, making the entire expression true. This is a tautology. Therefore, the answer is (∨,∨).
JEE Main · 2022 · 28 Jul 2022 · Shift 1 · Single correct option