<p>An ideal gas is allowed to expand both reversible and irreversibly in an isolated system. If&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>T</mi><mi>i</mi></msub></math>&nbsp;is the initial temperature and&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>T</mi><mi>f</mi></msub></math>&nbsp;is the final temperature, which of the following statements is correct?</p>