Question

What percent of Ca by weight is present in \(CaCO_3\) ?

• A. \(\text{40}\)
• B. \(\text{48}\)
• C. \(\text{96}\)
• D. \(\text{12}\)

Hint:

To find the percent composition of an element, divide its atomic mass by the molar mass of the compound and multiply by 100.

Answer 1

The Correct Option is A

Understanding the Molar Mass and Percentage of Ca in CaCO₃

The molar mass of \( \text{CaCO}_3 \) is calculated as follows:

\[ \text{Molar mass of } \text{CaCO}_3 = 40 + 12 + (16 \times 3) = 100 \, \text{g/mol} \]

The percentage of Ca in \( \text{CaCO}_3 \) is given by:

\[ \frac{40}{100} \times 100 = 40\% \]

Selecting the correct option. Since the calcium content is 40%, the correct answer is (A) 40.