47) A beam of alpha particles is incident on a target of lead. A particular alpha particle comes in ?head-on? to a particular lead nucleus and stops 6.5??10^?14?m away from the center of the nucleus. (This point is well outside the nucleus.) Assume that the lead nucleus, which has 82 protons, remains at rest. The mass of the alpha particle is 6.64??10^?27?kg What initial kinetic energy (in MeV) did the alpha particle have?

48) A triply ionized beryllium ion?Be³⁺, (a beryllium atom with three electrons removed), behaves very much like a hydrogen atom except that the nuclear charge is four times as great. (a) What is the ground-level energy of?Be³⁺?? How does this compare to the ground level energy of the hydrogen atom?

49) A triply ionized beryllium ion?Be³⁺, (a beryllium atom with three electrons removed), behaves very much like a hydrogen atom except that the nuclear charge is four times as great. What is the ionization energy of?Be³⁺?? How does this compare to the ionization energy of the hydrogen atom?

50) A triply ionized beryllium ion?Be³⁺, (a beryllium atom with three electrons removed), behaves very much like a hydrogen atom except that the nuclear charge is four times as great. For the hydrogen atom, the wavelength of the photon emitted in the n =2 to n=1 to transition is 122 nm. What is the wavelength of the photon emitted when a?Be³⁺?ion undergoes this transition?

51) What percentage of the mass of an atom is concentrated in the nucleus?