(R)-2-Methoxybutane is treated with one equivalent of HI at low temperature. Iodide attacks the carbon that is least hindered. What is the chiral organic product?

The protonated ether is attacked at the methyl carbon (SN2), so the $\mathrm{C}-\mathrm{O}$ bond at the stereocentre is never broken and the configuration is retained spatially. The priorities are $\mathrm{OR}$ (or $\mathrm{OH}$) $>$ $\mathrm{C}{}_2\mathrm{H}{}_5$ $>$ $\mathrm{CH}{}_3$ $>$ H in both ether and alcohol, so the descriptor does not change. The product is (R)-butan-2-ol with $\mathrm{CH}{}_3\mathrm{I}$.