To find the internal energy of gas we can use
[tex]U = \frac{f}{2}nRT[/tex]
here given that
Number of moles (n) = 7 moles
Temperature T = 40 + 273 = 313 K
degree of freedom(f) = 5 (for diatomic gas)
now by above formula
[tex]U = \frac{5}{2}* 7 * 8.31 * 313[/tex]
[tex]U = 45518.03 J[/tex]
So it is approximately 45500 J (option C)
