SECOND QUARTERLY EXAMINATION IN SCIENCE 8 S.Y. 2025 – 2026

After Democritus’ early idea of indivisible particles, who first developed a scientific atomic theory based on experimental evidence?

• J.J. Thomson
• John Dalton
• Ernest Rutherford
• Niels Bohr

Which scientist discovered the electron using a cathode ray tube experiment?

• James Chadwick
• Niels Bohr
• J.J. Thomson
• Democritus

How did Rutherford’s gold foil experiment change the atomic model?

• It proved atoms are indivisible.
• It showed electrons orbit the nucleus in fixed paths.
• It revealed the existence of a dense, positively charged nucleus.
• It discovered neutrons in the nucleus.

Why was Bohr’s model of the atom considered an improvement over Rutherford’s model?

• It included neutrons in the nucleus.
• It explained how electrons are arranged in energy levels.
• It showed atoms are made of protons and electrons only.
• It proved atoms are solid spheres.

Which sequence correctly represents the historical development of the atomic model?

• Bohr → Dalton → Thomson → Rutherford
• Dalton → Thomson → Rutherford → Bohr
• Thomson → Rutherford → Dalton → Bohr
• Rutherford → Bohr → Thomson → Dalton

According to the diagram, which particles are found inside the nucleus?

• Electrons only
• Protons and neutrons
• Neutrons and electrons
• Protons and electrons

Which subatomic particle is shown orbiting around the nucleus in the diagram?

• Proton
• Neutron
• Electron
• Nucleon

Based on the diagram, why are electrons placed in shells around the nucleus?

• To balance the mass of the atom
• To organize them by energy levels
• To protect the nucleus
• To keep them away from neutrons

What does the presence of two electron shells in the diagram suggest about the atom?

• It is unstable
• It has more than two protons
• It has more than two electrons
• It has no neutrons

Based on the diagram, which statement best describes the arrangement of particles in a simple atom?

• Electrons are grouped inside the nucleus with protons and neutrons.
• Protons and neutrons are located in the nucleus, while electrons orbit in shells.
• Neutrons and electrons are found in the outer shell, while protons stay in the nucleus.
• All particles are evenly spread throughout the atom.