20. The radius of the atom is of the order of 1 Ao and the radius of a nucleus is of the order of fermi. How many magnitudes higher is the volume of an atom as compared to the volume of the nucleus?

 
Hint: Consider an atom and a nucleus as spheres.
Step 1: Find the volume of the atom and the nucleus.
 Radius of atom =1Ao=1010m Radius of nucleus =1 fermi =1015m Volúme of atom =VA=43πRA3 Volume of nucleus VN=43πRN3Step 2: Find the ratio.VAVN=43πRA343πRN3=RARN3=101010153=1015