Question

While elements and compounds can both be classified as pure substances because they have distinct properties and composition, __________ cannot be decomposed further.

Answer 1

Answer: elements

Explanation:-

Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions. Example: Cobalt $(Co)$

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water $(H_2O)$

$2H_2O\rightarrow 2H_2+O_2$

Thus element is the pure substance that cannot be decomposed further.