1.the definition of enthalpy is
A)U-PV
B)U-TS
C)U+PV
D)U+TS

2.in Joule-Thomson expansion, which of the following quantity remains constant
A)entropy
B)energy
C)enthalpy

3.which of the following is the correct physical meaning of enthalpy
  change?
A)heat absorbed by system at constant volume.
B)heat absorbed by system at constant pressure.
C)most work can be done by system at constant volume.
D)most work can be done by system at constant pressure.

4.which of the following is the correct definition of heat capacity?