Question

How many atoms of carbon would a young man be giving to his bride-to-be if the engagement ring contains 0.5 carat diamond? (1 carat = 200 mg of C-12)

• A. $5.02\times {10}^{21}$
• B. $5.02\times {10}^{23}$
• C. Avogadro number
• D. $4.06\times {10}^{21}$

Answer 1

The correct option is A $5.02\times {10}^{21}$

Mass of diamond $\left(C\right)=0.5\times 200\text{mg}$
$=100\text{mg}=100\times {10}^{-3}\text{g}=0.1\text{g}$
Number of moles of $C=\frac{0.1\text{g}}{12{\text{g mol}}^{-1}}$
$=\frac{1}{120}$ mole
Number of $C$ atoms $=\frac{1}{120}\times 6.023\times {10}^{23}$
$=5.02\times {10}^{21}$