Rutherford's experiment infers atomic emptiness and nuclear charge/mass, but not composition.

Steps:

• Observe that most α-particles pass undeflected, indicating atoms are mostly empty space (A).
• Note small-angle deflections from atom's overall mass, but large rebounds require concentrated mass in a tiny nucleus (B).
• Recognize rebounds occur due to electrostatic repulsion, proving the nucleus is positively charged (D).
• Conclude the experiment provides no data on neutral particles like neutrons, so nuclear composition (C) remains unknown.

Why C is correct:

• The scattering follows Coulomb's law for charged particle repulsion, detecting only positive charge and mass density, not neutral neutrons (discovered via separate neutron-proton scattering in 1932).

Why the others are wrong:

• A: Direct from undeflected particles traversing foil without interaction.
• B: Explained by Rutherford's formula for scattering, where large deflections imply dense central mass.
• D: Rebounds result from like-charge repulsion between α-particles and nucleus.

Final answer: C