Question

Calculate the actual mass of 0.25 gram atom of calcium

Answer 1

$.25 \: is \: gra m \: per \: atom$
$so \: actual \: mass = (25 \div 1000) \times 40$
$= 10$

Answer 2

1 gm of calcium,relative atomic mass =40

So,

0.25 gm of calcium mass =0.25*40

then,

The answer is :10