1. The problem statement, all variables and given/known data The Ratio of the nuclear radius to the atomic radius of an element near the middle of the periodic table is most nearly a) 10^-2 b) 10^-5 c) 10^-8 d) 10^-11 e) 10^-14 2. Relevant equations 3. The attempt at a solution I am completely lost. Can someone tell me what they mean by radius of nucleus? My mere guess is that it could be approximated to be equal to the radius of hydrogen. Also, how can one compute the atomic radius? If anyone here knows 'back of the envelope' approach to this problem, please help!