How many gram atoms and atoms are there in 10 grams of calcium ?

(i) 40 g of calcium atoms represents $\to$ 1gram atom

10 g of calcium atoms represents $\to$ $x$ gram atoms

Then we will get,

$x=\frac{10}{40}=0.25\text{\hspace{0.17em}gram\hspace{0.17em}atoms}$

(ii) 40 g of calcium atoms $=6.023\times {10}^{23}\text{atoms}$

10 g of calcium atoms $=y$

$y=\frac{10}{40}\times 6.023\times {10}^{23}=1.50\times {10}^{23}\text{\hspace{0.17em}atoms}$

Therefore, 10 g of Ca contains 0.25 gram atoms and $1.50\times {10}^{23}$atoms.