Explanation

• Bleaching powder: CaOCl₂
• Chemical name: Calcium oxychloride.
• Main uses: Bleaching and disinfection.
• CaCl₂: Calcium chloride.
• Ca(OH)₂: Calcium hydroxide (slaked lime).

Last verified on 03-09-2026

Explanation

• Marconi invented Radio.
• Radio was invented in 1895.
• Guglielmo Marconi was an Italian inventor.

Last verified on 12-08-2026

Explanation

• Main Cause: Freon / CFCs
• Effect: Breaks down O₃ molecules → more UV-B radiation
• Other Contributors: Halons, carbon tetrachloride
• Result: Skin cancer, cataracts, climate impact

• The Montreal Protocol (1987) aimed to reduce CFC emissions
• Ozone layer protects Earth from harmful ultraviolet rays

Explanation

• Ibn al-Haytham presented the theory of reflection and refraction of light.
• He is also known as Alhazen.
• His work, particularly his "Book of Optics", is titled Kitab al-Manazir, written during 1011–1021.
• Born: c. 965 (c. 354 AH) Basra, Buyid Emirate
• Died: c. 1040 (c. 430 AH)[1] (aged around 75) Cairo, Fatimid Caliphate

Last verified on 02-09-2026

Explanation

• Venus comes closest to Earth when it is between Earth and the Sun.

• Minimum distance: about 24 million miles (≈ 38 million km).

• This close approach occurs roughly every 584 days.

Additional Information:

• Mercury can be about 33 million miles away when Venus is on the far side of the Sun.

Last verified on 17-01-2026

Explanation

• Ozone (O₃) is mainly found in the Stratosphere, called the ozone layer.
• It absorbs harmful ultraviolet (UV) radiation from the sun, protecting life on Earth.
• Located roughly 15–35 km above the Earth’s surface.

Last verified on 17-01-2026

Explanation

Antoine Henri Becquerel was an engineer, physicist, Nobel laureate,

First person to discover evidence of radioactivity.

 He belonged to France.

Explanation

• Venus is called the Morning Star and Evening Star.
• It is the second closest planet to the Sun.
• It is the brightest planet and the hottest planet in the Solar System.
• It has no natural moon (satellite).
• It is also known as the "Black Planet".

Last verified on 21-07-2026

Explanation

• 24-karat (24K) gold is considered the "best"
• Purity: 99.9% pure gold.
• Color: Rich, deep, bright yellow.

Additional information

• 22K Gold: 91.7% pure gold. It is mixed with harder metals like silver or copper.
• 18K Gold: 75% pure gold. It is highly durable and excellent for diamond settings 
• Carat is the unit of measurement for the physical weight of diamonds/gold.

Last updated by NA on 16-07-2026

Explanation

• Nitrogen (N₂): 78%

Additional information:

• Oxygen (O₂): 21%
• Argon (Ar): 0.93%
• Carbon dioxide (CO₂): ~0.04%
• Other gases: ~0.03%

Last verified on 16-05-2026