Explanation

• Rusting of iron is a chemical change.
• Because iron reacts with oxygen and moisture to form rust (hydrated iron oxide).
• A new substance is formed, and the change cannot easily be reversed.
• Rusting is a slow oxidation process that occurs in the presence of oxygen and water.
• Other examples of chemical changes: Burning wood, cooking food, and digestion.

Last verified on 15-10-2026

Explanation

• Sir James Chadwick discovered the neutron in 1932.
• He was a British physicist.
• His discovery completed the basic picture of the atomic nucleus.
• He received the Nobel Prize in Physics in 1935 for this discovery.

Additional information:

• J. J. Thomson – Electron (1897)
• Ernest Rutherford – Atomic nucleus (1911) and Proton (1917)

Last verified on 03-07-2026

Explanation

• Diffusion is the natural movement of particles from an area of higher concentration to lower concentration without external force.
• It occurs in gases, liquids, and even solids to some extent.

Last verified on 14-10-2026

Explanation

• Aeroplanes fly in the troposphere.
• It is the lowest layer of the Earth's atmosphere.
• It extending up to about 12 km (7.5 miles) above the Earth's surface.
• The troposphere is where weather occurs, and it's the layer where aircraft operate.
• It typically cruising at altitudes between 30,000 to 40,000 feet (9,100 to 12,200 meters).

Additional information:

• Stratosphere: Contains the ozone layer.
• Mesosphere: Most meteors burn up here.
• Thermosphere: Includes much of the ionosphere and auroras.

Last verified on 12-10-2026

Explanation

• The electromagnetic force acts between electrically charged particles.
• It causes both attraction and repulsion between charged particles.
• It is responsible for electricity, magnetism, light, and chemical bonding between atoms.

Additional information:

• Gravitational force: Acts between objects with mass and energy.
• Strong nuclear force: Holds quarks together and helps bind atomic nuclei.
• Weak nuclear force: Responsible for processes such as beta radioactive decay.

Last verified on 12-10-2026