Question

The radius of a nucleus of mass number 64 is 4.8 fermi. Then the mass number of another nucleus having radius of 4 fermi is \(\frac {1000}{x},\) where x is ____.

Answer 1

Correct answer is : 27

\(R = R _0A^{1/3}\)

\(R ^3 \propto A\)

\(\left(\frac {4.8}{4}\right)^3 = \frac {64}{A}\)

\(=\frac {64}{A }= (1.2)^3\)

\(A = \frac {64}{1.44 \times 1.2} = \frac {1000}{x}\)

\(x = \frac {144 \times 12}{64} = 27\)