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The mass of a quantity of NiCl2
is 24.6 g. How many formula units are in the sample?
A. 1.1 3 1023 NiCl2
formula units
B. 1.9 3 1027 NiCl2
formula units
C. 3.2 3 1023 NiCl2
formula units
D. 5.3 3 10–21 NiCl2
formula units

Answer :

Not sure, is it :
B.
 1.9 3 1027 NiCl2
formula units

Answer: The correct answer is Option A.

Explanation:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Given mass of nickel chloride = 24.6 g

Molar mass of nickel chloride = 129.6 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of }NiCl_2=\frac{24.6g}{129.6g/mol}=0.19mol[/tex]

Formula units is defined as lowest whole number ratio of ions in an ionic compound. It is calculate by multiplying the number of moles by Avogadro's number which is [tex]6.022\times 10^{23}[/tex]

We are given:

Number of moles of nickel chloride = 0.19 moles

Number of formula units = [tex]0.19\times 6.022\times 10^{23}=1.1\times 10^{23}[/tex]

Hence, the correct answer is Option A.

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