Question:medium

Which of the following is/are not true ?
I) If 1 is not a prime number, then 2 is not a prime number.
II) e is a vowel and \(12\times 3 = 36\)
III) It is not true that 14 is a composite number and 3 is even number.
IV) \(\sqrt{5}\) is an irrational number, but \(3+\sqrt{5}\) is a complex number.

Show Hint

Check each statement using truth tables for if-then, and, and not.
Updated On: Oct 1, 2026
  • Only I and IV
  • Only I
  • Only II and III
  • Only I, II and IV
Show Solution

The Correct Option is B

Solution and Explanation

Step 1: Evaluate every statement as true or false:
I: $F$ (implication with true hypothesis, false conclusion). II: T and T gives T. III: $\sim(T \land F) = \sim F = T$. IV: T "but" T gives T.

Step 2: Pick the false ones:
The question asks for those that are not true. Only I is false.

Step 3: Option check:
Option (B) "Only I" is the match.

Final Answer:
Only I is not true, option (B). \[ \boxed{\text{Only I}} \]
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