In the group $$(G\,{ \otimes _{15}})$$, where $$G = \{ 3,6,9,12\} $$, $${ \otimes _{15}}$$ is multiplication modulo 15, the identity element is

A group (G *) has 10 elements. The minimum number of elements of G, which are their own inverses is

A graph G has m vertices of odd degree and ‘n’ vertices of even degree. Then which of the following statements is necessarily true?

Which of the following is not a group with respect to the given operation?