If the ratio of the radius of a nucleus with 61 neutrons to that of helium nucleus is 3 , then the atomic number of this nucleus is

Step-by-step solution

The radius is directly proportional to 1 3 power of mass number, i.e., R ∝ A 1 3 Or A 1 A 2 = R 1 R 2 3 = 1 3 3 = 1 27 ⇒ A 2 A 1 = 27 ⇒ A 2 = A 1 × 27 = 4 × 27 = 108 ⇒ Z 2 = A 2 - 61 = 108 - 61 = 47