Question

the atomic mass of calcium is 40. how many atoms are present in 2 gram calcium ?

Answer 1

40g Ca = 6.022 ×10^23atoms of Ca
Therefore,
2g Ca= 6.022×10^23×2/40
=3.011 ×10^22 atoms of Ca

Answer 2

No. of atoms in 2 g of calcium
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As the atomic mass of calcium is 40g.
so ,
this 40 g is can be said to be one mole of calcium atom.

By the Avogadro's law-
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One mole of any substances contain the number of molecules or atoms equal to 6.022×10^23.

So here,
Number of moles of calcium (n) =mass of the calcium(m) / Molecular mass of calcium (M)

n = 2/40 mole

n= 1/20 mole

One mole of any substances contain the =6.022×10^23. atoms

1/20 mole will contain
=(1/20)×(6.022×10^23)

= 3.011×10^22 atom will be contained in 2 grams .