A binary operation \(\oplus\) is defines on the set of all positive integers by a \(\oplus\) b = ab for all positive integers a, b. Which of the following properties does NOT hold?

A.

closure

B.

identity

C.

positive

D.

inverse

Correct answer is D

a \(\oplus\) b = ab

The set of all national rules Q, is closed under the operations, additions, subtraction, multiplication and division. Since a \(\oplus\) b = ab; b \(\oplus\) a = ba = ab

The number 1 is the identity element under multiplication