What is heterogeneous mixture?

(A) It is matter that has a fixed or definite composition.

(B) Water,  

(C) It does not have a uniform composition throughout the sample.

(D) It is the simplest type of pure substance, containing only one type of atom.

(E) Substances that are physically mixed with uniform composition but not chemically combined.

(F) It contains two or more elements chemically combined in a specific proportion.

Classify these substances. More than one answer may apply in each case. N_2 element compound pure substance homogeneous mixture heterogeneous mixture solution O_2 element compound pure substance homogeneous mixture heterogeneous mixture solution N_2O element compound pure substance homogeneous mixture heterogeneous mixture solution Air (mostly N_2 and O_2) element compound pure substance homogeneous mixture heterogeneous mixture solution

Classify these substances. More than one answer may apply in each case. N_2 element compound pure substance homogeneous mixture heterogeneous mixture solution O_2 element compound pure substance homogeneous mixture heterogeneous mixture solution N_2O element compound pure substance homogeneous mixture heterogeneous mixture solution Air (mostly N_2 and O_2) element compound pure substance homogeneous mixture heterogeneous mixture solution