The alcohol shown is dehydrated with acid, and the secondary cation can undergo a 1,2-hydride shift to a tertiary cation. Counting E and Z isomers as different compounds, how many distinct alkenes can form in total from the cations?

The alcohol is 2,4-dimethylpentan-3-ol. The unrearranged secondary cation can lose only the tertiary hydrogens, giving 2,4-dimethylpent-2-ene (the two sides are equivalent). A hydride shift gives a tertiary cation that gives the same alkene plus 2,4-dimethylpent-1-ene. The total is 2 distinct alkenes.