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A signature, written in carbon pencil weighs $1 \mathrm{mg}$. What is the number of carbon atoms present in the signature?
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Verified Answer
The correct answer is:
$0.502 \times 10^{20}$
Number of carbon atoms
$$
\begin{aligned}
&=\frac{\text { mass }}{\text { molar mass }} \times 6.023 \times 10^{23} \\
&=\frac{10^{-3}}{12} \times 6.023 \times 10^{23} \\
&=5.02 \times 10^{19}=0.502 \times 10^{20}
\end{aligned}
$$
$$
\begin{aligned}
&=\frac{\text { mass }}{\text { molar mass }} \times 6.023 \times 10^{23} \\
&=\frac{10^{-3}}{12} \times 6.023 \times 10^{23} \\
&=5.02 \times 10^{19}=0.502 \times 10^{20}
\end{aligned}
$$
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