Question

The number of formula units of calcium fluoride `CaF_(2)` present in 146.4 g of `CaF_(2)` (The molar mass of `CaF_(2)` is 78.08 g/mol) is
A. `1.129xx10^(24) CaF_(2)`
B. `1.146xx10^(24) CaF_(2)`
C. `7.808xx1-^(24) CaF_(2)`
D. `1.877xx10^(24) CaF_(2)`

Answer 1

Correct Answer - A
Number of moles of `CaF_(2)=146.4/78.08=1.875`
`:.` No. of formula units `=1.875xxN_(A)`
`=1.875xx6.023xx10^(23)=11.29xx10^(23)=1.129xx10^(24)`