Explanation

• The law that states mass can neither be created nor destroyed is the Law of Conservation of Mass.
• This law states that mass remains constant in a chemical reaction.
• Matter cannot be created or destroyed, only transformed.

Last verified on 02-04-2026

Explanation

• The usual gases used for lifting airships are hydrogen and helium.
• Hydrogen is the lightest known gas and thus has great lifting capacity,
• Helium is not as buoyant but is far safer than hydrogen because it does not burn.

Last verified on 01-04-2026

Explanation

• Short-sightedness is called Myopia.
• It is corrected by a concave lens.
• This lens is thin in the center and thick at edges.
• It helps light focus on the retina correctly.
• Without correction, distant objects look blurred.

Additional information:

• Long-sightedness is called Hypermetropia.
• It is corrected by a convex lens.
• This lens is thick in the center and thin at edges.
• It helps light focus on the retina properly.
• Without correction, near objects look blurred.

Last verified on 07-06-2026

Explanation

• The Cerebellum controls body balance and coordination.
• It helps in smooth movement of muscles.
• It is also involved in simple learned (conditioned) responses.
• It works with other brain parts to maintain posture.
• Damage to it causes loss of balance and shaky movements.

Last verified on 07-06-2026

Explanation

Surface area = 4πr², Volume = 4/3πr³.  

Surface area is just derivative of volume w.r.t r.

2πr is circumference of a circle, not volume at all.

Last verified on 07-06-2026

Explanation

• Smog is a form of air pollution formed by smoke + fog.
• It mainly occurs in big cities due to vehicle and factory emissions.
• It reduces visibility and causes breathing problems.
• Smog is a serious environmental and health hazard.

Last verified on 06-06-2026

Explanation

• South Pole is called the "dark side of the Moon".
• "Dark" means "unknown" instead of "lacking sunlight".

Last verified on 06-06-2026

Explanation

• According to scientists, the universe has about 100 billion galaxies.
• Earlier estimates from the Hubble Space Telescope suggested similar numbers.
• Modern studies show it may be between 100–200 billion galaxies.
• Some older estimates even suggested up to 2 trillion galaxies (later revised).

Last verified on 06-06-2026

Explanation

• Oceans play the most important role in regulating Earth’s temperature and climate.
• They absorb heat from the Sun and distribute it across the planet.
• Ocean currents control weather patterns globally.
• They help maintain Earth’s temperature balance.

Last verified on 06-06-2026

Explanation

• Mangrove forests act as barriers against cyclones.
• Mangroves reduce erosion by trapping sediments, stabilizing the coastal zone and thus protecting the coast from storm surges and cyclones.
• Mangroves in Pakistan are found along the coastline of Sindh and Balochistan.

Last verified on 06-06-2026