Question

Which of the following pairs have the same number of atoms?

(i) \[\ce{16 g of O2 (g) and 4 g of H2(g)}\]

(ii) \[\ce{16 g of O2 and 44 g of CO2}\]

(iii) \[\ce{28 g of N2 and 32 g of O2}\]

(iv) \[\ce{12 g of C(s) and 23 g of Na(s)}\]

Answer 1

(iii) \[\ce{28 g of N2 and 32 g of O2}\]

(iv) \[\ce{12 g of C(s) and 23 g of Na(s)}\]

Explanation:

(iii) Number of atoms of nitrogen = `"Mass"/"Atomic mass" xx 6.023 xx 10^23`

= `28/14 xx 6.023 xx 10^23`

= `2 xx 6.023 xx 10^23`

(iv) Number of atoms of carbon = `12/12 xx 6.023 xx 10^23`

= `6.023 xx 10^23`

Number of atoms of sodium = `23/23 xx 6.023 xx 10^23`

= `6.023 xx 10^23`