Question

Helium is preferred to be used in balloons instead of hydrogen because it is

• A. Incombustible
• B. Lighter than hydrogen
• C. More abundant than hydrogen
• D. Non-polarizable

Hint:

Hydrogen is lighter than helium, but helium is preferred in balloons because helium is non-flammable.

Answer 1

The Correct Option is A

Concept:
Both hydrogen and helium are lighter than air. Therefore, both can provide lifting power in balloons. But safety is the most important factor. Hydrogen is highly inflammable, while helium is non-flammable.

Step 1: Compare hydrogen and helium.
Hydrogen is the lightest gas. But hydrogen can catch fire easily. It forms explosive mixtures with air.

Step 2: Understand helium.
Helium is a noble gas. It is chemically inert and does not burn. Therefore, helium is much safer than hydrogen for filling balloons.

Step 3: Meaning of incombustible.
Incombustible means: \[ \text{does not burn} \] Helium is incombustible. This is the main reason it is preferred in balloons.

Step 4: Check the options.
Option (A) Incombustible is correct.
Option (B) is incorrect because helium is not lighter than hydrogen. Hydrogen is lighter.
Option (C) is not the reason.
Option (D) is not the practical reason for using helium in balloons. Hence, the correct answer is: \[ \boxed{(A)\ \text{Incombustible}} \]