Question

Statement I: Formula unit mass is used to calculate the mass of ionic compounds.

Statement II: Formula unit mass is calculated by adding the atomic masses of all the ions involved in the compound.

• A. Only statement I is true
• B. Only statement II is true
• C. Both statements are true
• D. Both statements are false

Answer 1

The correct option is C Both statements are true

Formula unit mass is used to calculate the mass of ionic compounds. It is the sum of the atomic masses of all the ions in the compound.

For example, ${\text{MgCl}}_2$ is an ionic compound formed by the ions $M{g}^{2+}$ and $C{l}^{-}$.

The formula unit mass of ${\text{MgCl}}_2$ = atomic mass of Mg + (2 $\times$ atomic mass of Cl) = 24 + (2 $\times$ 35.5) = 95 u.