[UPSC IFoS 2014] Particle Physics (Q273, 8M)

Explain why each of the following reactions is forbidden :

(i) p + p \rightarrow p + p + n

(ii) p + p \rightarrow p + \pi^+ + \gamma

(iii) \Xi^0 \rightarrow n + \pi^0

(iv) \Lambda \rightarrow p + \pi^0

(v) $ u_e + p \rightarrow n + e^+$