In which of the following processes does the internal energy of a system remain constant?

Which of the following is a correct statement for a thermodynamic system?

Which of the following is true for heat and temperature?

Assertion : Absolute values of internal energy of substances cannot be determined.
Reason : It is impossible to determine exact values of constituent energies of the substances.

If a chemical reaction is accompanied by the evolution of heat,it is

Calculate the work done when $2$ moles of an ideal gas expand from a volume of $5 \ dm^3$ to $7 \times 10^{-3} \ m^3$ against a constant external pressure of $2.02 \times 10^5 \ Nm^{-2}$. (in $kJ$)