試題詳解

19. Rubidium–87 decays by beta decay with a half-life of 4.9×10¹⁰ years. How many 87Rb atoms are in a moon rock sample that has a rubidium decay rate of 3500 disintegrations per hour?
(A)9.0×10¹⁶ atoms
(B)4.3×10⁻⁴ atoms
(C) 2.2×10¹⁸ atoms
(D)2.5×10¹⁴ atoms
(E)2.6×10¹⁵ atoms