1. 1s^2 2s^2 2p^4 2. 1s^2 2s^2 2p^5 3.[Ar]4s^2 3d^10 4p^3 4. [Ar] 4s^2 3d ^10 4p^4

so which two electronic configurations represents elements that would have similar chemical properties. not sure how to do this

and shouldn't the electronic configuration for 3 and 4 be 3.[Ar]3d^10 4s^2 4p^3 4. [Ar]3d^10 4s^2 4p^4 because when you fill the d sub levels there energy drops.