A sample of $\mathrm{AlF}_{3}$ contains $3.0 \times 10^{24} \mathrm{~F}^{-}$ ions. The number of formula…

A sample of $\mathrm{AlF}_{3}$ contains $3.0 \times 10^{24} \mathrm{~F}^{-}$ ions. The number of formula unit of this sample are
  1. $9 \times 10^{24}$
  2. $3 \times 10^{24}$
  3. $0.75 \times 10^{24}$
  4. $1.0 \times 10^{24}$

Solution

An, AlF $_{3}$ the number of $\mathrm{F}$ is 3 for one $\mathrm{AlF}_{3}$ molecule $3 \mathrm{~F}^{-} \equiv 1$ formula unit of $\mathrm{AlF}_{3}$
$3.0 \times 10^{24} \mathrm{~F}^{-} \equiv \frac{1}{3} \times 3.0 \times 10^{24} \mathrm{AlF}_{3}$ units

Asked in: JEE-TOPICTESTS-CHEMISTRY

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