A gas occupies 2 litres at stp. It is provided 300 joule heat so that its volume becomes 2.5 litres at 1 atom. The change in its internal energy is.

Dear User,
ΔU = q + W
W = -PΔV         (work of expansion)
or, W = -1 (2.5 - 2) = 0.5 litre-atm
          = -0.5 x 101.3 J 
         = -50.65 J
q= 300 J
Therefore, ΔU = 300 J + (-50.65 J)
                       = 249.35 J