Question

Mass of one atom of the element A is 3.9854×10^-23 g. How many atoms are contained in 1g of element A is?

Answer 1

In any element or substance, the number of atoms contained in 1 mole is 6.023 × 10²³ atoms. This is Avogadro's number and is constant in 1 mole of every substance.

mass of 1 atom = mass of a mole of atoms / 6.022 x 10²³

That is molar mass = Avogadro's number × mass of 1 atom

molar mass for A = 6.022 x 10²³ × 3.9854×10⁻²³
                            = 24

Molar mass of element A is 25g/mol


Find number of atoms in 1 gram of element:

If molar mass is 24 g/mol means 1 mole has 24g.

If 24g = 1 mole = 6.022 x 10²³ atoms

Then 1g = 6.022 x 10²³ × 1g/24g

              = 2.5091667 ×10²² atoms

Therefore  1g of element A has 2.5091667 ×10²² atoms

Answer 2

By cross multiplication