Particle conservation laws — UPSC CSE 2003 Physics PYQ

(i) State the conservation law which is violated in each of the following processes: (1) n \rightarrow p + e^- + r (2) \pi^- + p \rightarrow K^+ + K^- (3) \pi^- + p \rightarrow \Sigma^+ + K^- (4) \Sigma^- \rightarrow K^- + p + \bar{p} (ii) Draw a bcc lattice. Determine its primitive lattice vectors and calculate the packing fraction.