3,3-Dimethylbut-1-ene is heated with dilute aqueous $\mathrm{H}{}_2\mathrm{SO}{}_4$. The major alcohol is

Protonation gives the secondary cation $(\mathrm{CH}{}_3){}_3\mathrm{C}-\mathrm{CH}{}^{+}-\mathrm{CH}{}_3$. A 1,2-methyl shift gives the tertiary cation $(\mathrm{CH}{}_3){}_2\mathrm{C}{}^{+}-\mathrm{CH}(\mathrm{CH}{}_3){}_2$, which is trapped by water. The major alcohol is 2,3-dimethylbutan-2-ol, not the unrearranged 3,3-dimethylbutan-2-ol.