Option d: N and P
In a periodic table, elements within the same group have similar properties.
(a) K and He: Here, K (potassium) belongs to group 1 , alkali metals and He belongs to group 18, noble gas thus, they cannot have similar properties.
(b) Li and B: Here, Li (lithium) belongs to group 1, alkali metals and B (boron) belongs to group 13, it is the only non-metal in group 13. Thus, they cannot have similar properties.
(c) I and Ca: Here, I (iodine) belongs to group 17, halogen, they electronegative in nature and Ca (calcium) belongs to group 2, alkaline earth metal, they are electropositive in nature. Thus, they cannot have similar properties.
(d) N and P: Here, both N (nitrogen) and P (phosphorus) belongs to group 15, they both are non metals and have 5 electrons in their outermost shell thus, they both have similar properties.
Therefore, option (d) is correct.
