Which non metal is most reactive? Nitrogen, oxygen or neon?
Among oxygen, nitrogen and neon; oxygen is the most reactive. Neon is a noble gas and is, thus, (almost) inert, that is, non-reactive. A look at the electronic configurations of the three given elements will clarify things much better. The atomic numbers of nitrogen, oxygen and neon are 7, 8 and 10. The electronic configurations of each are:
Nitrogen: 1s2, 2s2, 2p3
Oxygen: 1s2, 2s2, 2p4
Neon: 1s2, 2s2, 2p6.
As we can see from the electronic configurations, neon has a fully filled outer shell and hence is non-reactive. Oxygen needs 2 more electrons to fill the outer shell, while nitrogen needs 3 electrons. Hence, it is much easier for oxygen to complete its octet, as compared to nitrogen and that is why, oxygen is more reactive than nitrogen.
Hope this helps.