Question

Calculate the number of moles present in 9.10 × 10¹⁶ kg of water.

• A. 0.9
• B. 1.8
• C. 4.5
• D. 5

Hint:

When calculating moles from mass, always convert grams to kilograms (if needed), then divide by the molar mass of the substance.

Answer 1

The Correct Option is D

The molar mass of water is 18 g/mol. Convert the mass of water to grams: \[ 9.10 \times 10^{16} \, \text{kg} = 9.10 \times 10^{19} \, \text{g} \] Now, use the molar mass to calculate the number of moles: \[ \text{Moles of water} = \frac{9.10 \times 10^{19} \, \text{g}}{18 \, \text{g/mol}} = 5 \times 10^{18} \, \text{mol} \]