Classify each of the following as an element, a compound, a homogeneous mixture, or a heterogeneous mixture:

Question:

Classify each of the following as an element, a compound, a homogeneous mixture, or a heterogeneous mixture:
(a) Seawater,
(b) Helium gas,
(c) Sodium chloride (table salt),
(d) A bottle of soft drink,
(e) A milkshake,
(f) Air in a bottle,
(g) Concrete.