Problem 6.308

Which of the following processes are forbidden by the law of conservation of lepton charge: (1) $n \rightarrow p+e^{-}+v$ (2) $\pi^{+} \rightarrow \mu^{+}+e^{-}+e^{+}$ (3) $\pi^{-} \rightarrow \mu^{-}+v$ (4) $p+e^{-} \rightarrow n+v$ (5) $\mu^{+} \rightarrow e^{+}+v+\tilde{v}$ (6) $K^{-} \rightarrow \mu^{-}+\tilde{v} ?$