Answer : The value of
of the gas is 2.79 Joules.
Explanation :
First we have to calculate the moles of helium.

Molar mass of helium = 4 g/mole

Now we have to calculate the heat.
Formula used :

where,
q = heat
n = number of moles of helium gas = 0.0125 mole
= specific heat of helium = 20.8 J/mol.K
= initial temperature = 310.0 K
= final temperature = 235.0 K
Now put all the given values in the above formula, we get:



Now we have top calculate the work done.
Formula used :

where,
w = work done
p = pressure of the gas = 1 atm
= initial volume = 1.21 L
= final volume = 0.99 L
Now put all the given values in the above formula, we get:



conversion used : (1 L.atm = 101.3 J)
Now we have to calculate the value of
of the gas.



Therefore, the value of
of the gas is 2.79 Joules.