Which of the following statements is correct about laws of conservation a) charge can be created but not destroyed
b) in absence of external torque , angular momentum remains conserved
c)under the action of conservative forces , potential energy of system remains conserved
d) under the action of non conservative forces total mechanical energy of systems remains conserved

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?