Balance the chemical equation with the correct coefficients:
NCI3
N2 +
Cl2

I’m not sure what your trying to say here.. can you clarify again?

Ithink that the answer is b

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).