Neopentyl alcohol (2,2-dimethylpropan-1-ol) is heated with conc. $\mathrm{H}{}_2\mathrm{SO}{}_4$. The major alkene formed is

A primary neopentyl cation is not stable and rearranges by methyl shift to the tertiary cation $(\mathrm{CH}{}_3){}_2\mathrm{C}{}^{+}-\mathrm{CH}{}_2\mathrm{CH}{}_3$. Saytzeff elimination then gives the more substituted alkene, 2-methylbut-2-ene.