Heat of reaction at constant volume is measured in which apparatus?

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

Explain the standard enthalpy of reaction.

Which among the following pairs represents extensive and intensive properties respectively?

Which among the following is $NOT$ a feature of a reversible process?

The internal energy change when a system goes from state $A$ to $B$ is $40 \, kJ/mol$. If the system goes from $A$ to $B$ by a reversible path and returns to state $A$ by an irreversible path,what would be the net change in internal energy?