Q138 / 200 · NEET 2006 · Physics

The radius of germanium (Ge) nuclide is measured to be twice the radius of ${ }_4^9 \mathrm{Be}$. The number of nucleons in Ge are:

  • Correct answer
    A
    72
  • B
    73
  • C
    74
  • D
    75

Solution

Nuclear radii $R=R_0 A^{1 / 3}$ Where $\quad R_0=1.2 \mathrm{fm}$ or $\quad R \propto(A)^{1 / 3}$ $\therefore \quad \frac{R_{H_e}}{R_{G_e}}=\frac{(a)^{\frac{1}{3}}}{(A)^{\frac{1}{3}}}$ or $\quad \frac{R_{H_e}}{2 R_{B^{\varepsilon}}}=\frac{(q)^{\frac{1}{3}}}{(\lambda)^{\frac{1}{3}}}$ Given $\quad R_{G e}=2 R_{B C}$ $(A)^{1 / 3}=2 \times(9)^{1 / 3}$ or $A=23 \times 9=8 \times 9=72$ $\therefore$ Number of nucleus is $\mathrm{Ge}$ is 72

Hence, the correct answer is option: 'A'.

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