$A$ $7.9 \text{ MeV}$ $\alpha$-particle scatters from a target material of atomic number $Z = 79$. From the given data, the estimated diameter of the nucleus of the target material is (approximately) . . . . . . $\text{m}$.
$\left[\frac{1}{4 \pi \epsilon_0} = 9 \times 10^9 \text{ Nm}^2/\text{C}^2\right.$ and electron charge $\left.e = 1.6 \times 10^{-19} \text{ C}\right]$

• A
  $5.76 \times 10^{-14}$
• B
  $1.44 \times 10^{-13}$
• C
  $2.88 \times 10^{-14}$
• D
  $1.69 \times 10^{-12}$