1. classify each of the following as a homogeneous or heterogeneous substance.
a. iron ore
b. quartz
c. granite
d. energy drink
e. oil-and-vinegar salad dressing
f. salt
g. rainwater
h. nitrogen

a. iron ore  - heterogeneous substance

(it contains a mixture of iron oxides)

b. quartz  - homogeneous substance

(it is the crystalline silicon dioxide SiO₂, which is a very pure form of SiO₂)

c. granite  - heterogeneous substance

(it as mixture of different oxides, mainly aluminium and silicon oxides)

d. energy drink  - heterogeneous substance

(a mixture of water, sugar, carbon dioxide and different substances that may boost concentration, like caffeine)

e. oil-and-vinegar salad dressing  - heterogeneous substance

(this salad dressing of oil and vinegar is composed of unsaturated triglycerides, acetic acid and water)

f. salt  - homogeneous substance

(sodium chloride NaCl)

g. rainwater  - homogeneous substance

(assuming the the atmosphere is clean, it is just pure water H₂O)

h. nitrogen - homogeneous substance

(it is the main component of air and it is a diatomic molecule N₂)

Explanation:

A homogenous substance is one that has a uniform composition in all its parts.

A heterogenous substance has different composition in their parts.

a. iron ore

Iron ore is a heterogenous substance in which the composition of its part are not uniform.

b. quartz

Quartz is a homogenous substance because it is made up of silica alone joined in a framework pattern.

c. granite

Granite is heterogenous because it is an aggregate of several minerals like quartz, feldspars e.t.c

d. energy drink

Energy drink is homogenous due to the uniformity of the mixture.

e. oil-and-vinegar salad dressing

This is a heterogenous substance

f. salt

Salt is a homogenous substance because all its parts are uniform

g. rainwater

Rainwater is homogeous substance

h. nitrogen

Nitrogen is homogeous substance

b is the correct answer

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