<p>A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>&#8710;</mo></math>U of the gas in joule will be:</p>