Explanation

• Copper (تانبا) is a good conductor of electricity.
• It allows electric current to flow easily.

Additional information:

• Metals are generally good conductors.
• Non-metals usually do not conduct electricity.
• Good Conductors: Copper, Silver, Gold, Aluminum, Graphite
• Bad Conductors: Plastic, Rubber, Wood, Glass, Air

Last verified on 07-06-2026

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 kidneys purify the blood in the human body.
• They remove waste materials and extra water.
• Kidneys help maintain the body’s chemical balance.
• Each person has two kidneys.
• They produce urine as a waste product.

Last verified on 07-06-2026

Explanation

• Because sound is just vibrating air, space has no air to vibrate and therefore no sound in a vacuum.
• Sound waves below 20 Hz are known as infrasound.
• Sound waves above 20 kHz are known as ultrasound.

Sound waves transmit a medium such as a gas, liquid, or solid.

• The speed of sound in air is about 343 meters per second.
• The sound travels at 1,481 m/s in water.
• The speed of sound in a vacuum is zero meters per second.

Last verified on 07-06-2026

Explanation

• Alexander Fleming discovered Penicillin
• At St. Mary's Hospital in London
• In September 1928.
• First true antibiotic used to treat bacterial infections.
• First patient treated was Albert Alexander, a 43-year-old policeman, on 12 February 1941

Last updated by NA on 23-April-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

• 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