Explanation:
(a) As per the mole concept, one mole of any atom contains [tex]6.022 \times 10^{23}[/tex] atoms or molecules, that is, Avogadro's number of atoms.
Therefore, 1 mole of [tex]H_{2}[/tex] = [tex]2 \times 6.022 \times 10^{23}[/tex] molecules
= [tex]1.2044 \times 10^{23}[/tex] molecules
1 mole of [tex]O_{2}[/tex] = [tex]2 \times 6.022 \times 10^{23}[/tex] molecules
= [tex]1.2044 \times 10^{23}[/tex] molecules
1 mole of [tex]F_{2}[/tex] = [tex]2 \times 6.022 \times 10^{23}[/tex] molecules
= [tex]1.2044 \times 10^{23}[/tex] molecules
Hence, there are equal number of molecules present in the given atoms.
(b) Mass of each given atom will be calculated as follows.
Mass = no. of moles × molar mass
As one molecule of [tex]H_{2}[/tex] contains 2 atoms of hydrogen.
So, mass of 1 mole of [tex]H_{2}[/tex] = [tex]2 mol \times 1.008 g/mol[/tex]
= 2.016 g
mass of 1 mole of [tex]O_{2}[/tex] = [tex]2 mol \times 15.999 g/mol[/tex]
= 31.996 g
mass of 1 mole of [tex]F_{2}[/tex] = [tex]2 mol \times 18.998 g/mol[/tex]
= 37.996 g
Thus, we can conclude that [tex]F_{2}[/tex] has the greatest mass.