Question

In an $\alpha -$particle scattering experiment, $\alpha -$particles of equal kinetic energy strike on a metal foil. If a large number of $\alpha -$particles go undeviated and have a small deflection, that means,

• A. the atomic number of the atoms in the foil is small.
• B. the atomic number of the atoms in the foil is large.
• C. the nucleus of the atoms in the foil is larger.
• D. the nucleus of the atoms in the foil is smaller.

Answer 1

The correct option is A the atomic number of the atoms in the foil is small.

The $\alpha -$particles are scattered due to the force of repulsion experienced by them due to the presence of positive charge present in the nucleus.
If a large number of $\alpha -$particles go undeviated and have a small deflection, clearly the magnitude of positive charge in the nucleus is smaller.

Hence, $\left(A\right)$ is the correct answer.