$B$ Decays Involving $η$ and $η'$ in the Light of the $B \to K η'$ Process

The observation by the CLEO Collaboration of the decay $B^+ \to K^+ \eta'$ with a branching ratio of about $7 \times 10^{-5}$ is shown to imply a significant but still uncertain contribution from the flavor-SU(3)-singlet component of the $\eta'$. By comparing this rate with others for decays of $B$ mesons to two pseudoscalar mesons, it is shown that the prospects for observing CP-violating asymmetries in certain modes such as $B^+ \to \pi^+ \eta$ and $B^+ \to \pi^+ \eta'$ are quite bright.