Question

The number of gram atoms in 3.2 g of Ca is

a. 3.2
b. 0.08
c. 0.8
d. 1.008

Answer 1

1 gram atom = 40 grams of Ca
? ---------------=3.2 grams of Ca

3.2/40 = 0.08

Answer 2

Answer: b. 0.08

Explanation: According to mole concept, 1 mole of every substance contains 1 gram atom.

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\textMolar mass}}$

$\text{Number of moles of calcium}=\frac{3.2g}{40g/mol}=0.08moles$

As 1 mole contains = 1 g atom

0.08 moles contain=$\frac{1}{1}\times 0.08=0.08gatom$