Explanation

• Common salt is chemically known as sodium chloride (NaCl).
• It is an ionic compound composed of sodium and chloride ions
• Representing a 1:1 ratio of sodium and chloride ions
• Formula: NaCl
• Melting point: 801 °C
• Density: 2.16 g/cm³
• Boiling point: 1,465 °C

Question updated on 11-02-2026

Explanation

Explanation

• WBCs survive for about 13–20 days, depending on the type.
• WBCs are also called Leukocytes.
• They protect the body against infections.
• They are produced in the bone marrow.

Important Note: The 13–20 days lifespan is not applicable to all WBCs; their lifespan varies according to type.

Explanation

• Nitrous oxide, commonly known as laughing gas.
• It is a colorless, non-flammable gas used in medicine.
• Nitrous oxide (N₂O) causes temporary laughing and relaxation.

Additional information:

• Nitrous oxide was discovered by Joseph Priestley in 1772.

Last verified on 18-01-2026

Explanation

• Total bones in adult human body = 206
• At birth = 270–300 bones (fuse to become 206)

The total bones of our body can be divided into:

• Axial skeleton = 80 bones
• Appendicular skeleton = 126 bones

Additional information:

• Newborn baby has 300 bones
• Longest bone = Femur
• Shortest bone = Stapes
• Bones in human skull = 22

Last verified on 30-03-2026

Explanation

Explanation

• Mercury is the closest planet to the Sun, followed by Venus.
• Called an inner planet because it orbits inside Earth’s orbit.
• Number of moons: 0 (Mercury has no natural satellites).
• Size: Smallest planet in the solar system.
• Nickname: Swift Planet, due to its fast orbit around the Sun (≈88 days per orbit).

Last verified on 17-03-2026

Explanation

• Geology means the study of the Earth.
• It is also called Earth Science or Geoscience.
• Geology studies the formation, structure, composition, and history of Earth.
• It also examines the processes acting on Earth, such as earthquakes, volcanoes, and erosion.
• A person who studies geology is called a geologist.

Last verified on 15-09-2026

Explanation

• Discoverer: Alexander Fleming
• Year of discovery: 1928
• Place: St. Mary's Hospital, London
• First patient treated with penicillin: Albert Alexander
• Date of first treatment: 12 February 1941

Last verified on 14-09-2026

Explanation

• O⁻ (O Negative) is the universal donor blood group.
• It can be transfused to A, B, AB, and O blood groups.
• O⁻ blood lacks A, B, and Rh (D) antigens.

Additional information:

• Universal Recipient: AB⁺ (AB Positive)
• ABO Blood Groups: A, B, AB, O
• Rh Types: Positive (+) and Negative (−)
• Total Common Blood Groups: 8 (A⁺, A⁻, B⁺, B⁻, AB⁺, AB⁻, O⁺, O⁻)

Last verified on 14-07-2026