Corpus is a Latin word, which. means body. In financial usage, it. means a collection of bonds, stocks, or other holdings, which. form the principal1 of a trust fund. The concept of corpus is closely linked to. the concept of trust.
Physical changes occur when objects or substances undergo a change that does not change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combine or break up to form new substances. In general a physical change is reversible using physical means.
Look at the enthalpy for the second equation, the one I reversed. Notice how the sign has changed also. This is an absolute requirement of using Hess' Law: reversing an equation means reversing the sign on the enthalpy value.