Question

Speed of sound in gas is of the same order as rms speed of its molecules

• A. True
• B. False

Answer 1

The correct option is B False

According to Maxwell, the root-mean-square speed, urms, of gas molecules with molar mass M at absolute temperature T is given by the equation:
$U_{rms}=\sqrt{3RT/M}$
where R = 8.314 J/K.mol, and the molar mass M must be expressed in kg/mole in order for the units to come out in m/s. This equation reveals that gas molecules, on the average, travel at very high speeds. These values correspond to 3040 miles per hour and 1150 mph, respectively. The speed of sound in a gas is about the same as the root mean square speed of the gas molecules. Thus the above statement is true.