Question

How many grams of neon will have the same number of atoms as 4g of calcium?

Answer 1

Molar mass of calcium = 40 g/mol
Therefore, 40 g of calcium = 1 mole of calcium
No of moles in 4 g = $\frac{4}{40}=0.1\mathrm{mol}$

Now, no of atoms in one mole of any substance remains constant, i.e 6.022 $\times$ 10²³

So 0.1 mol of calcium will contain same no of atoms as in 0.1 mol of neon.

Molar mass of neon = 20 g/mol
Therefore, 20 g of neon = 1 mole of neon​
0.1 mol will contain 2 g of neon
Hence 2 gm of neon will have the same no of atom as in 4 gm of calcium.