Question

Fill in the blanks:

Elements combine in a fixed proportion to form _____.

Answer 1

1. Compounds: A compound is a pure substance that is made up of two or more elements chemically combined in a fixed proportion by mass.
2. Example: Water is represented as ${\mathrm{H}}_2\mathrm{O}$ in which hydrogen and oxygen are present in the fixed proportion of $1:8$ by mass i.e., the atomic mass of $\mathrm{H}=1\mathrm{u},\mathrm{O}=16\mathrm{u}$.

Therefore, Water has the formula ${\mathrm{H}}_2\mathrm{O}$. Hence, $\text{2u : 16u = 1 : 8}$

Therefore, Elements combine in a fixed proportion to form compounds.