2-Bromo-2,3-dimethylpentane, CH3C(Br)(CH3)CH(CH3)CH2CH3, is heated separately with (i) sodium ethoxide in ethanol and (ii) potassium tert-butoxide in…

The $\beta$-hydrogens are on the two methyl groups at C-2 (giving the terminal alkene, 2,3-dimethylpent-1-ene) and on C-3 (giving the tetrasubstituted 2,3-dimethylpent-2-ene). The small base ethoxide gives the more substituted, more stable Zaitsev product. The bulky tert-butoxide cannot easily reach the crowded tertiary C-3 hydrogen and removes a less hindered methyl hydrogen instead, so the Hofmann product dominates.