Explanation

• The chemical name of chalk is Calcium carbonate.
• Its chemical formula is CaCO₃.
• It is a soft, white mineral.
• Commonly used in blackboard chalk and limestone.
• Found naturally in rocks and marine shells.

Last verified on 30-04-2026

Explanation

Composition of Air:

• Nitrogen → 78%
• Oxygen → 20.95%
• Argon → 0.93%
• Carbon dioxide → 0.04%
• Other gases → very small traces

Last verified on 30-04-2026

Explanation

• Vitamin A is essential for vision, skin health, and immune function.
• Its deficiency can lead to night blindness (poor ight vision) and other health problems.

Additional information:

• Dry skin and eyes
• Impaired immune function
• Poor wound healing
• Increased risk of respiratory and urinary tract infections

Last verified on 17-01-2026

Explanation

• The law of universal gravitation was proposed by Isaac Newton.
• He introduced it in 1687 in his famous book Principia.
• It explains that every object attracts every other object.
• The force depends on mass and distance.

Last verified on 27-04-2026

Explanation

• Mars is known as the Red Planet
• Because its surface is covered in iron oxide (rust) and has an orange-red appearance
• Fourth planet from the Sun
• Symbol ♂
• The largest volcano is Olympus Mons.
• Two moons: Deimos and Phobos.

Question updated on 08 march 2026