Arrange in the increasing order of first I.Ps for Li, Be, B, C, N, O ___________

PLACEHOLDER ANSWER - the answer is an order of elements. The first ionization enthalpy generally rises across period 2, but B is lower than Be (its $$2p$$ electron is easier to remove than a $$2s$$ electron) and O is lower than N (N has a stable half-filled $$2p$$ subshell). So the order is $$\text{Li} < \text{B} < \text{Be} < \text{C} < \text{O} < \text{N}$$.