Question

16. Which of the following is a noble gas?

• A. hydrogen
• B. helium
• C. oxygen
• D. nitrogen

Answer 1

The correct option is B

helium

Explanation for correct option:

(B) Noble gas:

• Noble gases are rare or inert gases that have stable configuration and do not react with any other substance generally.
• Valance shells are completely filled, that's why they do not react with other substances and thus, they are chemically inert.
• There are six naturally occurring noble gases, which are - Helium (He), Neon (Ne), Argon (Ar), Krypton(Kr), Xenon (Xe), and Redon (Rn).

So, among the given elements only helium (He) is a noble gas.

Explanation for incorrect option:

Other given elements, such that hydrogen (H₂), oxygen (O₂), and nitrogen (N₂) do not have completely filled outermost shells, so they are not noble gases. They are non-metals. Thus, the option (A), (C) and, (D) are incorrect.

Hence, the correct option is (B).