Question

which pair of elements has the most similar properties?
n and p
li and b
i and ca
k and he

Explanation:

Elements in the same group (vertical column) of the periodic table have similar properties. Nitrogen (N) and Phosphorus (P) are both in Group 15. Lithium (Li) is in Group 1 and Boron (B) is in Group 13. Iodine (I) is in Group 17 and Calcium (Ca) is in Group 2. Potassium (K) is in Group 1 and Helium (He) is in Group 18.

Answer:

N and P