Question

which of the following substances is an element?
a. methane (ch4)
b. brass (cu + zn)
c. carbon (c)
d. water (h2o)

Explanation:

Step1: Recall element definition

An element is a pure - substance made of only one type of atom.

Step2: Analyze option A

Methane ($CH_4$) is a compound made of carbon and hydrogen atoms.

Step3: Analyze option B

Brass is an alloy (a mixture) of copper and zinc.

Step4: Analyze option C

Carbon (C) is made of only carbon atoms, so it is an element.

Step5: Analyze option D

Water ($H_2O$) is a compound made of hydrogen and oxygen atoms.

Answer:

C. carbon (C)