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

Explanation

• Centrifugation is a separation method that uses rapid rotation to separate components according to their density.
• Cream contains fat globules that are less dense than the watery part of milk.

Additional information:

• Distillation: Separates substances based on differences in boiling points.
• Sublimation: A solid changes directly into a gas.

Last verified on 12-10-2026

Explanation

• The modern periodic table arranges elements in order of increasing atomic number.
• The atomic number is the number of protons present in the nucleus of an atom.
• Elements with similar chemical properties are placed in the same group (vertical column).
• The modern periodic law was established by Henry Moseley.

Last verified on 12-10-2026

Explanation

• A neutron has no electric charge, so it is electrically neutral.

Additional information:

• A proton has a positive charge (+1).
• An electron has a negative charge (−1).

Last verified on 07-10-2026