Question

number of atoms present in 142 grams of chlorine is

Answer 1

no. of moles = 142/35.5= 4
no. of atoms= 4×6.023×10^23
=24.09×19^23
=2.409×10^24
where , 35.5 is the atomic mass of the chlorine

Answer 2

We know that,

The number of atoms = $\frac{given mass}{molar mass}$× Avogadro number

Here,

Given mass = 142 g

We know that,

Molar mass of chlorine = 35·5 u

Avogadro number = 6·022×10²³

Therefore,

Number of atoms = $\frac{142}{35·5}$× 6·022×10²³

                             = 4× 6·022×10²³

                             = 24·08×10²³

The number of atoms present in 142 grams of chlorine is 24·08×10²³