Question

A sample of gas at 1 atm occupies volume amounting to 1 litre. Now it expands at constant temperature to 4 litres, find heat added to gas. Take ($\ln 2=0.693$).

• A. Zero
• B. 110 J
• C. 138.6 J
• D. 69.3 J

Answer 1

The correct option is C 138.6 J

For isothermal process
$Q=W$

$W=nRT\ln \left(\frac{V_f}{V_i}\right)$

$=PV\ln \left(\frac{V_f}{V_i}\right)$

$={10}^5\times {10}^{-3}\ln \left(\frac{4}{1}\right)$

$=200\ln 2$

$=200\times 0.693=69.3\times 2=138.6J$