Final answer:
The percent by mass of chlorine in the compound is 64%, calculated using the formula: (mass of chlorine/mass of compound) × 100%.
Step-by-step explanation:
To find the percent by mass of chlorine in the compound, we use the formula:
Percent by mass = (mass of the element/mass of the compound) × 100%
In this case, the mass of chlorine is 64 g and the mass of the compound is 100 g. Therefore, the calculation is:
(64 g / 100 g) × 100% = 64%
The percent by mass of chlorine in the compound is 64%.