Sound waves travel the fastest through which of the following?

A. cold gas

B. hot gas

C. Hot vacuum

D. Cold vacuum

The molecules in hot gas move faster than cold gas. This would allow sound waves to travel faster.

Vacuums, do not have air pressure to transfer energy, so sound would not be able to travel very fast.

The answer is B. Hot Gas.

Option B

Explanation:

Sound waves are mechanical waves it means they require a material medium for their propagation.

So, sound cannot travel through hot vacuum or cold vacuum.

The velocity of sound waves is directly proportional to the square root of absolute temperature of gas.

As the temperature of hot gas is more so sound travel fastest in hot gas.