Question

Which has more number of atoms, $100$ grams of sodium or $100$ grams of iron. [Given, the atomic mass of $NA=23u,Fe=56u$]

Answer 1

Given, Mass of Na = 100g ; Molar mass of Na= 23 g

No. of moles of Na = $\frac{100}{23}$ = 4.347

No. of atoms of Na = 4.35 x $N_A$ ($N_A$ is the Avagadro's Number)

Given, Mass of Fe = 100g ; Molar mass of Fe= 56 g

No. of moles of Fe = $\frac{100}{56}$ = 2.10

No. of atoms of Fe = 2.10 x $N_A$ ($N_A$ is the Avagadro's Number)

So, Na has more no. of atoms.