I was looking at the organic chemistry 8th Ed textbook by Paula Yurknais Brucie. On page 509, I found this: I think about it for a while and I am doubting that it is wrong. I believe the hydride ion itself cannot act as a nucleophile for SN2. (not really sure but I guess it is too small and too ...

In problem 6, part 6.5 of the 2020 IChO, a thermodynamic cycle is given for "one mole of monoatomic perfect gas": To my understanding, the answer should be $\pu{0 J}$ for both steps since $ΔG=0$ for any reversible process, which $A \rightarrow B$ and $D \rightarrow C$ are. But, the solution belo...