Nitrogen (N), oxygen (O), chlorine (Cl), neon (Ne), and argon (Ar) are all elements that occur as a gas at room temperature (20°C). Using the periodic table, which pair of gases has the most similar properties?
The gases that has the most similar properties is
Neon (Ne) and Argon (Ar)
explanation
From periodic table both Argon (Ar) and Neon(Ne) are element in group 18 which are referred to as noble gases.
Noble gases are inert since they have eight (8) valence electrons ( electrons in their outermost shell) which make them stable( neither gain or lose electrons)