Chapter 2:
                        12, 18, 24, 27, 45, 46, 56, 64, 66, 67

Hints/comments:

2.27: Remember that H is a state function, so you are free to "invent" a reversible path that gets you from the initial state to the final state. The process here is:

H₂O(l, -10C) -> H₂O(s, -10C)

2.64: The temperature at which you can obtain the molar internal energy of combustion is (298 - 1.707) = 296.293 K

2.67: The process here is:  H₂SO₄(l) -> H₂SO₄(ai) and note that the heat released by this solvation process is absorbed by the number of moles of water in the solution.