Question:medium

Which of the following is not true:
(A) Zero is a prime number.
(B) One is an integer.
(C) 31 is a whole number but not a prime number.
(D) -31 is an integer but not a whole number.
Choose the correct answer from the options given below:

Show Hint

Zero is not prime, and 31 is itself a prime number.
  • (A) and (C) only.
  • (A), (B) and (D) only.
  • (B), (C) and (D) only.
  • (C) and (D) only.
Show Solution

The Correct Option is A

Solution and Explanation

Test each option for its truth value directly.
(A) claims zero is prime. A prime number has exactly two distinct positive divisors, and zero has infinitely many divisors, so (A) is false.
(B) claims one is an integer, which is correct, so (B) is a true statement.
(C) claims 31 is a whole number but not prime. Since $31$ has no divisors other than $1$ and $31$, it is prime, so the second half of (C) is wrong, making the whole statement false.
(D) claims $-31$ is an integer but not a whole number. Whole numbers start from $0$ and go upward, so a negative number cannot be whole, so (D) is fully correct.
Only (A) and (C) turn out false, so those are the ones that are not true.
\[\boxed{\text{(A) and (C) only}}\]
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