Question

A sample of ${CaCO}_3$ has $Ca=40$%, $C=12$% and $O=48$%. If the law of constant proportion is true then the weight of calcium in $5g$ of a sample of ${CaCO}_3$ from another source will be:

• A. $0.20g$
• B. $2.0g$
• C. $2.5g$
• D. $4.0g$

Answer 1

Answer: (B)

$2.0g$

In $100g$ of sample $\to$ $40g$ of $Ca$

$5g$ of sample $\to$$\frac{40}{100}\times 5=2.0g$ of $Ca$