Which of the following numerical expressions gives the number of moles in 5.0 g of CaO?

• A. 5.0 \times (40.08 + 16.00)
• B. 5.0 \div 40.08
• C. 5.0 \div (40.08 + 16.00)
• D. (40.08 + 16.00) \div 5.0

Answer: (C)

Verified step by step guidance

1. Identify the chemical formula of the compound, which is CaO, consisting of calcium (Ca) and oxygen (O).
2. Calculate the molar mass of CaO by adding the atomic masses of calcium and oxygen: \$40.08 + 16.00$ grams per mole.
3. Recall that the number of moles is calculated by dividing the mass of the sample by its molar mass, using the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}}\).
4. Substitute the given mass (5.0 g) and the calculated molar mass into the formula: \(\text{moles} = \frac{5.0}{40.08 + 16.00}\).
5. This expression correctly represents the number of moles in 5.0 g of CaO.