Question

The approximate external work done, when 1 g
helium is heated through 1°C at constant pressure
is
(1) 8J
(2) 4J
(3) 2J
(4) 1 J​

Answer 1

Answer:

Explanation:-PV = nRT == 1/2× 8.314 × 274 ==appx 1J

Answer 2

Answer:

External work done in heating 1 g of helium through 1°C at constant pressure is approximately equal to 2J.

Explanation:  

Given Temperature,  $T=1^{o} C$

mass of helium, $m=1g$

Number of moles in 1g of Helium, $n=0.25mole$

Universal gas constant, $R=8.314Jmol^{-1} K^{-1}$

Helium heated at constant pressure, therefore work done is

                   $W=\int P dV$  

                       $=nR\int\limits^{T_{2} }_ {T_{1} } dT=nR(T_{2} } - {T_{1})$

                       $=nR\times 1=nR$

                       $=0.25\times8.314\approx2J$

Therefore, external work done is approximately equal to 2J.