Question

In a thermodynamic process, pressure of a fixed mass of a gas is changed in such a manner that the gas releases 20 J of heat and 8 J of work is done on the gas. If initial internal energy of the gas was 30 J, what will be the final internal energy?

Solution

Correct option is

18 J

 

We know,  Since heat is released by the system,

 

As work is done on the gas, 

 

       

Or     

SIMILAR QUESTIONS

Q1

Molar specific heat at constant volume Cv for a mono-atomic gas is:

Q2

>Cvas in the case of Cp:

Q3

The following sets of values for Cv and Cp of a gas have been reported by different students. The units are cal/gm-mole-K. Which of these sets is most reliable?

Q4

A reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by 62oC, the efficiency of the engine is doubled. The temperatures of the source and sink are:

Q5

We consider a thermodynamic system. If  represents the increase in its internal energy and the work done by the system, which of the following statements is true?

Q6

If the ratio of specific heats of a gas at constant pressure to that at constant volume is , the change in internal energy of the given mass of gas, when the volume changes from to 2V at constant pressure P is:

Q7

A Carnot engine uses first an ideal mono-atomic gas () and then an ideal diatomic gas () as its working substance. The source and sink temperatures are 411oC and 69oC respectively and the engine extracts 1000 J of heat from the source in each cycle. Then:

Q8

If R is universal gas constant, the amount of heat needed to raise the temperature of 2 moles of an ideal mono-atomic gas from 273 K to 373 K when no work is done is:

Q9

The temperatures of inside and outside of a refrigerator are 273 K and 303 K respectively. Assuming that the refrigerator cycle is reversible, for every joule of work done, the heat delivered to the surroundings will be nearly:

Q10

 

An ideal gas is taken through a cyclic thermo-dynamical process through four steps. The amounts of heat involved in these steps are:

    respectively. The corresponding works involved are:  respectively. The value of W4 is: