Question

In $1911$, the physicist Ernest Rutherford discovered that atoms have a tiny, dense nucleus by shooting positively charged particles at a very thin gold foil. A key physical property which led Rutherford to use gold that it was.
$\left( {\text{A}} \right)$ Electrically conducting
$\left( {\text{B}} \right)$ Highly malleable
$\left( {\text{C}} \right)$ Shiny
$\left( {\text{D}} \right)$ Non-reactive

Answer 1

Rutherford gold foil experiment:
Scientists bombarded a thin gold foil of thickness approximately ${8.610^{ - 6}}\;$ cm with a beam of alpha particles in a vacuum.
Alpha particles are positively charged particles with a mass of about four times the mass of a hydrogen atom and are found in radioactive natural substances.
Since gold it is highly malleable, producing sheets that can be only a few atoms thick, thereby ensuring smooth passage of the alpha particles.
A circular screen is coated with zinc sulfide surrounding the foil.
Since the positively charged alpha particles possess mass and move very fast, it was assumed that they would penetrate the thin gold foil and land themselves on the screen, producing fluorescence in the part they incident.

Complete step-by-step solution:
Though most of the alpha particles behaved as expected, a fraction of particles that got scattered by angles greater than ${90^ \circ }$.
About $1$ in every $2000$ particles that got scattered by a full ${180^ \circ }$, i.e., they retraced their path after hitting the gold foil.
A highly concentrated positive charge at the center of an atom that caused an electrostatic repulsion of the particles strong enough to bounce them back to their source.
The particle which has got deflected by a huge angle passed because it was close to the said concentrated mass.
Most of the particles moved undeviated as there was no obstruction to their path, proving that the majority of an atom is empty.
Rutherford concluded that since the central core could deflect the dense alpha particles, it shows that almost the entire mass of the atom is concentrated there.
Rutherford named it the “nucleus” after experimenting with various gases.

Hence, the correct option is B.

Note: Rutherford performed his experiment on bombarding thin gold foil with alpha particles contributed immensely to the atomic theory by proposing his nuclear atomic model.
The nuclear model of the atom consists of a small and positively charged dense interior surrounded by a cloud of electrons.