Which of the following is not a state function?

Given below are two statements $ : $
Statement $I :$ When a system containing ice in equilibrium with water $(\text{liquid})$ is heated, heat is absorbed by the system and there is no change in the temperature of the system until whole ice gets melted.
Statement $II :$ At the melting point of ice, there is absorption of heat in order to overcome intermolecular forces of attraction within the molecules of water in ice, and the kinetic energy of molecules is not increased at the melting point.
In the light of the above statements, choose the correct answer from the options given below $ : $

For an adiabatic change,which of the following is true?

In a reversible isothermal process,the change in internal energy is

Explain the standard enthalpy of reaction.

$A$ gas is allowed to expand against a constant external pressure of $2.5 \ bar$ from an initial volume '$x$' $L$ to a final volume of $4.5 \ L$. If the amount of work done is $5 \ dm^3 \ bar$,what is the value of '$x$' (in $L$)?