Which atom, O or N, has the greater atomic radius?

Maybe you should get some from your teacher and learn more so you can get your grades up and maybe study a bit more

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).