Explanation

• Isotones are atoms of different elements having the same number of neutrons.

• Their atomic numbers are different but neutron numbers remain equal.

• Example: Carbon-14 and Nitrogen-15 both have 8 neutrons.

• Isotones may have different chemical properties because they belong to different elements.

• The term “isotone” was introduced in nuclear chemistry studies.

Last verified on 09-05-2026

Explanation

• Beta radiation has intermediate penetrating power between alpha and gamma rays.

• Alpha rays have the least penetrating power, while gamma rays have the highest.

• Beta particles can pass through paper but are stopped by thin aluminum sheets.

• Beta radiation consists of fast-moving electrons or positrons.

• Ernest Rutherford classified alpha and beta radiations during radioactive studies.

Last verified on 09-05-2026

Explanation

• Almost all the mass of an atom is concentrated in its nucleus.
• The nucleus contains protons and neutrons, which are much heavier than electrons.
• Electrons revolve around the nucleus but contribute very little to atomic mass.
• The nucleus is located at the center of the atom.
• Ernest Rutherford discovered the nucleus through the gold foil experiment in 1911.

Last verified on 09-05-2026

Explanation

• Coal energy is considered suitable for base-load power generation because coal can be stored and supplied continuously.
• Base-load power means electricity supplied continuously to meet constant demand.
• Coal power plants can operate 24 hours a day.
• Major base-load energy sources: Coal, Nuclear, Hydroelectric, Natural Gas, Geothermal.
• China is the world’s largest producer and consumer of coal.

Last verified on 09-05-2026

Explanation

• Quantum theory states that energy is not emitted or absorbed continuously.
• Instead, energy is exchanged in fixed small units called quanta.
• This idea was introduced by Max Planck in 1900.
• It explains atomic behavior and radiation more accurately than classical physics.
• Therefore, atomic energy changes occur in separate packets.

Last verified on 08-05-2026

Explanation

• The photoelectric effect occurs when light ejects electrons from a metal surface.
• Each metal has a minimum required frequency called the threshold frequency.
• If the incident light frequency is below this value, electrons are not emitted.
• Increasing intensity cannot overcome insufficient frequency.
• Therefore, the photoelectric effect stops completely.

Last verified on 08-05-2026

Explanation

• Ocean tides on Earth are caused by gravitational forces.
• The strongest and most influential source is the nearest large celestial body.
• Although the Sun also contributes, its effect is weaker than expected due to distance.
• The Moon’s proximity makes its gravitational pull dominant in tidal formation.
• Therefore, the Moon is the main driver of ordinary ocean tides.

Last verified on 08-05-2026

Explanation

• Natural gas is widely used for cooking and heating in homes.
• It is efficient, convenient, and relatively clean compared to other fossil fuels.
• It can be transported easily through pipelines.
• It burns with less pollution and no solid residue (ash).
• Its main advantage is safe, continuous, and clean supply.

Last verified on 08-05-2026

Explanation

• Energy sources are divided into renewable and non-renewable.
• Renewable energy is naturally replenished and does not run out.
• Fossil fuels like coal, petroleum, and natural gas are exhaustible.
• Wind energy is continuously available in nature.
• It is clean and does not depend on limited reserves.

Last verified on 08-05-2026

Explanation

• The nucleus is the control center of the cell.
• It contains genetic material (DNA) that directs all cell activities.
• Without the nucleus, the cell loses coordination and regulation.
• Basic processes like growth, protein synthesis, and division stop.
• The most fundamental function affected first is control of activities.

Last verified on 08-05-2026