Test for hydrogen gas which observation is expected?

• A. Squeaky pop with a lit splint
• B. Relights a glowing splint
• C. Turns limewater cloudy
• D. Damp red litmus turns blue

Answer: (A)

Hydrogen is highly flammable and burns quickly when lit. When a small amount of hydrogen gas is ignited, it reacts with the oxygen in the air to form water, and the rapid combustion inside the closed space creates a sharp, squeaky pop. That distinct sound is the hallmark of hydrogen being present.

This differs from other tests: a glowing splint is rekindled by oxygen, not hydrogen; limewater goes cloudy with carbon dioxide; damp red litmus turns blue with a basic gas like ammonia. So the observed squeaky pop with a lit splint best indicates hydrogen.