Question

The number of Carbon atoms in 1g of CaCO₃ is:

• A. 6.02×10²³
• B. 6.02×10²¹
• C. 3.0125×10²²
• D. 1.204×10²³

Answer 1

The correct option is B

6.02×10²¹

Explanation for correct option (B)

• Given mass of Calcium carbonate (${\mathrm{CaCO}}_3$) is 1g
• The molar mass of Calcium carbonate (${\mathrm{CaCO}}_3$) is 100g
• To find the number of atoms, we have to calculate the number of moles as well as the number of molecules in 1g of CaCO_3.
• $$\begin{gathered} \mathrm{number}\mathrm{of}\mathrm{moles}=\frac{\mathrm{given}\mathrm{mass}\mathrm{of}{\mathrm{CaCO}}_3}{\mathrm{molar}\mathrm{mass}\mathrm{of}{\mathrm{CaCO}}_3} \\ \mathrm{number}\mathrm{of}\mathrm{moles}=\frac{1}{100} \\ \mathrm{number}\mathrm{of}\mathrm{moles}=0.01 \\ \mathrm{number}\mathrm{of}\mathrm{moles}=\frac{\mathrm{number}\mathrm{of}\mathrm{molecules}}{6.02\times {10}^{23}} \\ \mathrm{number}\mathrm{of}\mathrm{molecules}=6.02\times {10}^{21} \end{gathered}$$
• Each molecule of ${\mathrm{CaCO}}_3$ contains one carbon atom. So, $6.02\times {10}^{21}$ will have $6.02\times {10}^{21}$carbon atoms.
• Hence, option B is the correct answer.