Which ionisation needs less energy than this process?
P(g)→P+(g)+e− \text{P(g)} \rightarrow \text{P}^{+}(\text{g}) + e^{-} P(g)→P+(g)+e−S(g)→S+(g)+e−\text{S(g)} \rightarrow \text{S}^{+}(\text{g}) + e^{-}S(g)→S+(g)+e−
N(g)→N+(g)+e−\text{N(g)} \rightarrow \text{N}^{+}(\text{g}) + e^{-}N(g)→N+(g)+e−
Cl(g)→Cl+(g)+e−\text{Cl(g)} \rightarrow \text{Cl}^{+}(\text{g}) + e^{-}Cl(g)→Cl+(g)+e−
P+(g)→P2+(g)+e−\text{P}^{+}(\text{g)} \rightarrow \text{P}^{2+}(\text{g}) + e^{-}P+(g)→P2+(g)+e−