Question

Which of the following substances is an element? A. water B. table salt C. iron oxide D. hydrogen

Answer 1

D. Hydrogen

an element is a pure substance that cannot be broken down

Answer 2

Answer:

$\boxed {\tt D. \ Hydrogen}$

Explanation:

An element has a uniform composition, cannot be broken down by chemical change, every atom has the same atomic number, and can be found on the Periodic Table.

Water is made of hydrogen and oxygen atoms (H₂O) so it is not an element.

Table salt is made of sodium and chloride atoms (NaCl) so it is not an element.

Iron oxide is made up of iron and oxygen atoms, so it is not an element.

Hydrogen is an element. It can be found on the Periodic Table as element H.

The correct answer is D. Hydrogen