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This question has Statement -1 and Statement-2. Of the choices given after the Statements, choose the one that best describes the two Statement.

 

Statement 1: The internal energy of a perfect gas is entirely kinetic and depends only on absolute temperature of the gas and not on its pressure or volume.

Statement 2: A perfect gas is heated keeping pressure constant and later at constant volume. For the same amount of heat the temperature of the gas at constant pressure is lower than that at constant volume.
 

Option: 1

Statement 1 is true, Statement 2 is true

Statement 2 is the correct explanation of statement -1


Option: 2

Statement 1 is true, Statement 2 is false.


Option: 3

Statement 1 is true, Statement 2 is true

Statement 2 is the not the correct explanation of statement -1


Option: 4

Statement 1 is false, Statement 2 is true


Answers (1)

best_answer

 

 

 

 

 

Internal energy of a system is the energy possessed by the system due to molecular motion and molecular configuration.

so \ \ Internal \ \ energy = $u=u_{k}+u_{p}$

For an ideal gas there is no molecular attraction

so\ u_{p}=0\Rightarrow u=u_k

 

(i.e., Internal energy =internal kinetic energy) 

\text { and } u=u_{k}=\frac{3}{2} \mu R T

So Statement 1 is true, 

\text { At constant pressure }\Rightarrow (\Delta Q)_{P}=\mu C_{p} \Delta T\\ \text { At constant volume }\Rightarrow (\Delta Q)_{V}=\mu C_{V} \Delta T

As \ \ C_{P}>C_{v} \therefore(\Delta T)_{P}<(\Delta T)_{v}

So  Statement 2 is true

But Statement 2 is the not the correct explanation of statement -1

So option 3 is correct option

Posted by

Rishi

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