5g of a gas is contained in a rigid container and is heated from 15°C to 25°C. Specific heat capacity of the gas at constant volume is 0.172 cal g^{–1}°C^{–1} and the mechanical equivalent of heat is 4.2 J cal^{–1}. Calculate the change in the internal energy of the gas.

**Given:**

Mass of the gas(m) = 5g

Change in temperature(dT) = 10°C

Specific heat at constant volume(C_{v}) = = 0.172 cal g^{–1}°C^{–1}

Mechanical equivalent of heat = 4.2 J cal^{–1}

**Formula used:**

Change in internal energy = mC_{v}dT

Where,

m = Mass of the gas

C_{v} = Specific heat at constant volume

dT = Change in temperature

Also, we know,

Heat(Joule)= Mechanical equivalent of heat× Heat(cal)

Putting the values in the above formula, we get

= (5x10x0.172) cal

= 8.6 cal = (8.6x4.2)J

= 36.12 J (Answer)

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