Explanation

• Carbon dioxide (CO₂) is used in fire extinguishers.
• It extinguishes fire by displacing oxygen and cooling the burning material.
• CO₂ fire extinguishers are especially effective for electrical and flammable liquid fires.
• Carbon dioxide is a colorless and non-flammable gas.
• It leaves no residue after use.

Explanation

• Amylase breaks down starch.
• Starch → Maltose + smaller sugars.
• Found in saliva and pancreatic juice.
• Salivary amylase starts starch digestion in the mouth

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

Explanation

• Nicolaus Copernicus proposed the heliocentric model.
• Heliocentric means the Sun is at the center.
• Earth and other planets revolve around the Sun.
• Proposed in the 16th century.
• Ptolemy supported the geocentric model (Earth-centered).

Explanation

• Ice is less dense than water, so it floats.
• Archimedes’ Principle explains the buoyant force acting on floating ice.
• The buoyant force acts upward against gravity.
• Formula: FB = p Vg
• Key point: An object floats when buoyant force = its weight.

Explanation

• Light Year is the distance that light can travel in one year.
• The distance light travels in one year is known as light year.
• 1 light year is equal to 9.5 x 10¹²km.

Last verified on 30-03-2026

Explanation

• Vitamin C deficiency causes scurvy.
• It can cause bleeding/loose gums, easy bruising, and poor wound healing.
• Other signs include rough skin, corkscrew hair, and red spots around hair follicles.
• Rickets is mainly caused by Vitamin D deficiency.

Last verified on 13-09-2026

Explanation

• Carbon dioxide (CO₂) — the main greenhouse gas causing global warming.

Additional information:

• Methane (CH₄) — potent, from livestock and fossil fuels.
• Nitrous oxide (N₂O) — from fertilizers and industry.
• Water vapor — natural, amplifies warming.
• Fluorinated gases — synthetic, very strong effect.

Explanation

• Heinrich Wilhelm Waldeyer coined the word "neuron" in 1891.
• He based it on the ancient Greek word for sinew or cord.
  
• Neuron theory/doctrine emerged at the end of the 19th century.
• Core claim — Nerve tissue = individual cells; each is a genetic, anatomic, functional, and trophic unit.
  
  Last updated by NA on 09-09-2026

Explanation

• Cumulonimbus clouds are tall, dense clouds associated with thunderstorms.
• They can produce hail, heavy rain, lightning, and strong winds.
• Hail forms when strong updrafts inside these storm clouds carry water droplets upward, where they freeze.

Last verified on 09-09-2026