Question

Give one word/a a few words for each of the following.

The substance with fixed chemical and physical properties.

Answer 1

A substance with fixed chemical and physical properties is a compound.

• A compound is a substance made up of two or more elements chemically combined in a fixed proportion by mass.
• Water $\left({\mathrm{H}}_2\mathrm{O}\right)$, for example, is a chemical combination made up of two elements, Hydrogen and Oxygen, chemically united in a fixed mass ratio of $1:8$ (atomic masses:$$\begin{gathered} \mathrm{H}=1\mathrm{u},\mathrm{O}=16\mathrm{u}, \\ \mathrm{hence}{\mathrm{H}}_2:\mathrm{O}=2\mathrm{u}:16\mathrm{u} \\ \mathrm{or}1:8 \end{gathered}$$).