Alpha particle is equivalent to B. Helium atom (2 protons, 2 neutrons)
As you go down a group on the periodic table, atomic radii tend to increase because elements with larger atomic numbers have more occupied electron levels which take up more space surrounding the nucleus.
I hope this helps.
group 1 elements are metals with<u> low</u> density
The molar mass of nitrogen is 14.0067amu or just 14amu.
