Question

A chemist is studying an unknown substance. He can break it into its elemental components only by using chemical means. Based on this observation, how should the unknown substance be classified?

Answer 1

Pure substance

Step-by-step explanation:

Matter can be broadly classified into two categories: Pure substances and Mixtures (homogenous and heterogenous mixtures).

The simplest form of a pure substance is an element which cannot be broken down any further. When two or more elements combine, they form a compound which is also a pure substance. Thus, pure substances are systems that are either composed of a single type of element or a single type of molecule.

For example salt (NaCl) is a compound which is composed of elements: sodium (Na) and chlorine (Cl). These elements (in fact ions, Na+ and Cl-) are held together by a chemical bond. Thus, a pure substance like NaCl can be broken down into its elements through chemical means.

The unknown substance in the given question can therefore be classified as a pure substance

Answer 2

The answer would be:

Pure substance: specifically a compound

Pure substances can be categorized into compounds and elements. A compound is a pure substance that cannot be broken down physically, but it can be broken down through chemical means. It is this property that differentiates it from mixtures. Mixtures can be broken down by physical and/or chemical means.

Elements on the other hand, cannot be broken down at all because it is in its simplest form and is also considered as a pure substance.