Atomic Structure: Discovery of the Neutron

Which subatomic particle was the last to be discovered among the three primary components of an atom?

• Protons

• Electrons

• Neutrons

• Quarks

What property of protons in the nucleus led scientists to hypothesize the existence of a neutral particle?

• Their negative charge attracting electrons.

• Their ability to bond with other atoms.

• Their positive charge causing mutual repulsion.

• Their role in determining an element's identity.

What did early scientists observe when comparing the mass of one helium atom to hydrogen atoms?

• One helium atom was lighter than two hydrogen atoms.

• One helium atom had the same mass as two hydrogen atoms.

• One helium atom had a mass equivalent to four hydrogen atoms, despite having only two protons.

• One helium atom had a mass equivalent to one hydrogen atom.

When alpha particles were directed at beryllium, boron, or lithium, what type of radiation was observed to be released?

• Positively charged protons

• Negatively charged electrons

• Radiation without an electric charge

• High-energy gamma rays

In the second part of Chadwick's experiment, what substance was used to interact with the uncharged radiation, leading to the emission of protons?

• Gold foil

• Paraffin wax

• Water

• Lead

Based on the observation that the unknown radiation could eject protons from paraffin with significant force, why was it concluded that this radiation could not be gamma rays?

• Gamma rays carry a positive charge, unlike the observed radiation.

• Gamma rays are too heavy to effectively transfer energy to protons.

• Gamma rays are too light to cause protons to shoot out at high speeds.

• Gamma rays are absorbed by paraffin, preventing proton ejection.

What subatomic particle, characterized by having no electric charge and a mass similar to a proton, was discovered by James Chadwick in 1932?

• Electron

• Proton

• Neutron

• Photon