MCQ Detailed View

The gas most commonly used in balloons and airships is helium (He). Helium is the second lightest element in the periodic table, after hydrogen, and it has unique properties that make it ideal for lifting objects in the air. Its density is about one-seventh of air, which means it provides enough buoyant force to lift balloons and airships off the ground.

Historically, hydrogen gas was used in airships because it is even lighter than helium. However, hydrogen has a dangerous drawback — it is highly flammable. This caused several tragic accidents, the most famous being the Hindenburg disaster of 1937, where a hydrogen-filled German airship caught fire and exploded. After such incidents, hydrogen use was discontinued in airships due to safety concerns.

Helium, in contrast, is chemically inert and non-flammable. It belongs to the noble gases group in the periodic table, which are known for their stability and lack of chemical reactivity. Because of this, helium is much safer to use, even though it provides slightly less lift compared to hydrogen.

Helium is extracted mainly from natural gas reserves, where it occurs in small concentrations. The gas is separated and stored under pressure for various uses. Apart from balloons and airships, helium has important applications in cryogenics, medical imaging (MRI machines), scientific research, and as a protective gas in welding.

In everyday life, helium-filled balloons are widely used for decoration and celebrations because they float safely in the air without risk of fire. Airships and scientific balloons also rely on helium for safe, long-duration flights.

Thus, the correct answer is Helium (Option A). Its lightweight, inert, and non-flammable nature makes it the safest and most practical gas for balloons and airships.