If a graph is plotted between the nuclear mass density ( ) and the mass number ( A ) of various stable nuclei, the shape of the curve is best described as:

Step-by-step solution

The radius of a nucleus R is related to its mass number A by the formula R = R₀ A^ 1/3 . The volume of the nucleus is V = 4 3 R^3 = 4 3 R₀^3 A . The mass of the nucleus is approximately m A , where m is the average mass of a nucleon. Therefore, the nuclear mass density is = Mass Volume = m A 4 3 R₀^3 A = 3m 4 R₀^3 . This shows that the nuclear mass density is a constant, independent of the mass number A . Thus, the graph of versus A is a straight line parallel to the mass number axis ( A -axis). Answer: A straight