Question

Helium (He), oxygen (O), carbon (C), and selenium (Se) are all nonmetals. Using the periodic table, which pair of these nonmetals has the most similar properties?

Answer 1

using the periodic table, the pair of non metals that has the most similar properties would be :
Oxygen and Selenium
at the periodic table, these both located on the same period

hope this helps

Answer 2

Answer: Oxygen and Selenium are the non-metals that will show similar properties.

Explanation:

It is known that neutral elements which contain same number of valence electrons will show similar chemical properties though their physical properties can be different.

Therefore, elements of same group tend to similar chemical properties.

So, out of the given options both oxygen and selenium belongs to same group therefore they show similar chemical properties.