Q14 of 31 Page 94

Calculate the number of atoms in 39.4 g gold. Molar mass of gold is 197g mole-1.

We know,


Molar mass=Mass of Avogadro’s number of atoms


=6.023×1023 atoms.


Given, mass of gold, m=39.4 g


Molar mass of gold=197g mole-1


Now,197 g of gold contain 6.023×1023 atoms


i.e. 1g of gold contain atoms


∴ 39.4 g of gold contain atoms = 1.20×1023 atoms


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