Question

What weight of calcium contains the same number of atoms as are present in 3.2 g of
sulphur?

Answer 1

We know that,

Weigh of 1 mole of an element = Atomic mass of the element

Number of atoms in 1 mole of an element = 6.023 x10²³.

So, 32 g of S contains 6.023x10²³ atoms.

Therefore, 3.2 g of S will contain ( 6.023x10²³ x 3.2)/32 = 6.023x10²² atoms of S.

Now, weight of 6.023x10²³ atoms of Ca is 40 g.

Thus, weight of 6.023x10²² atoms of Ca will be ( 6.023x10²² x 40) / 6.023x10²³ = 4 g.