Speed of Sound in Air

The speed of sound in air depends mainly on temperature. A commonly used approximate value for the speed of sound in dry air at 20°C is around 343 meters per second ($ \approx 343 \, \text{m/s}$).

Comparing Options to Standard Value

Let's evaluate each option:

• 12000 m/s: This is significantly faster than the typical speed of sound.
• 3400 km/s: To compare, convert this to m/s: $ 3400 \, \text{km/s} \times 1000 \, \text{m/km} = 3,400,000 \, \text{m/s} $. This value is extremely high, far exceeding the speed of sound.
• 340 m/s: This value is very close to the standard approximate speed of sound in air.
• 3 x 10⁸ m/s: This value, $ 3 \times 10^8 \, \text{m/s} $, is the speed of light in a vacuum, not sound.

Final Determination

Based on the comparison, 340 m/s is the closest value to the speed of sound in air among the given options.