Q. 33

# 4.0 g of helium occupies 22400 cm^{3} at STP. The specific heat capacity of helium at constant pressure is 5.0 cal K^{–1} mol^{–1}. Calculate the speed of sound in helium at STP.

Answer :

**Given:**

4.0 g of helium occupies 22400 cm^{3} at STP.

The specific heat capacity of helium at constant pressure is 5.0 cal K^{–1} mol^{–1} = 21J K^{–1} mol^{–1}

⇒

⇒

At STP the pressure P is 1.013×10^{5}Pa.

The velocity of sound will be where P is the pressure of the gas, V is the volume and M is the mass of the gas.

Thus putting the values given, we get,

The speed of sound in helium is m/s.

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4.0 g of helium occupies 22400 cm^{3} at STP. The specific heat capacity of helium at constant pressure is 5.0 cal K^{–1} mol^{–1}. Calculate the speed of sound in helium at STP.

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