Question

Which has more number of atoms, 100 grams of sodium or 100 grams of iron (given, atomic mass of Na = 23 u, Fe = 56 u)? [3 MARKS]

Answer 1

Each point: 1.5 Marks

1. Atomic mass of Na = 23 u (Given)

Then, gram atomic mass of Na = 23 g

Now, 23 g of Na contains = 6.022 x 10²³ g number of atoms

Thus, 100 g of Na contains = $6.022\times \frac{{10}^{23}}{23}\times 100$ number of atoms

= 2.6182 x 10²⁴ number of atoms.

2. Again, atomic mass of Fe = 56 u (Given)

Then, gram atomic mass of Fe = 56 g

Now, 56 g of Fe contains = 6.022 x 10²³ g number of atoms

Thus, 100 g of Fe contains = $6.022\times \frac{{10}^{23}}{56}\times 100$ number of atoms

= 1.0753 x 10²⁴ number of atoms.