General Science

A lactometer is a hydrometer used to estimate the specific gravity/density of milk. It is commonly used as a quick indicator of milk quality.

A hygrometer measures humidity, the amount of water vapour in air. A psychrometer is a type of hygrometer using wet- and dry-bulb temperatures.

The spin-drying stage of a washing machine uses centrifugation. Rapid rotation forces water outward through the perforated drum, separating it from clothes.

World AIDS Day is observed every year on 1 December. It was first observed in 1988 and focuses on HIV/AIDS awareness, prevention, treatment and remembrance.

Sericulture is the rearing of silkworms for silk production. Apiculture concerns bees, floriculture flowers, and silviculture the cultivation and management of forests.

Acetic acid (ethanoic acid), formula CH₃COOH, is the characteristic acid in vinegar.

28 February 1928 marks C. V. Raman’s discovery of the Raman Effect; India observes National Science Day on this date.

The 44th Constitutional Amendment Act, 1978 removed the Right to Property from Fundamental Rights; it is now protected as a constitutional legal right under Article 300A.

The Jallianwala Bagh massacre occurred on 13 April 1919 during the tenure of Viceroy Lord Chelmsford.

The Sun is composed mainly of hydrogen and helium. Hydrogen accounts for about 73–75% of the Sun’s mass, while nuclear fusion in its core converts hydrogen into helium and releases energy.

The kidneys are the principal excretory organs. They filter blood and remove nitrogenous wastes, excess water and salts through urine; their structural and functional units are called nephrons.

LPG is mainly a mixture of the hydrocarbons propane and butane. It is stored as a liquid under pressure and vaporizes for use as a cooking fuel.

A normal human somatic cell contains 46 chromosomes, arranged in 23 pairs. Gametes such as sperm and ova contain 23 chromosomes.

Calcium is essential for the formation and maintenance of strong bones and teeth. It is also important for muscle contraction, nerve function and blood clotting.

Nitrous oxide (N₂O) is commonly called laughing gas. It has been used medically as an analgesic and anaesthetic, although uncontrolled inhalation can be dangerous.

Raindrops tend towards a spherical shape because of surface tension. Surface tension minimizes the surface area of a liquid for a given volume.

Carotene, especially beta-carotene, contributes to the yellowish colour of cow’s milk and dairy fat. It is a fat-soluble pigment obtained largely through the animal’s diet.

Cinchona bark contains quinine and related alkaloids that were historically important in the treatment of malaria. Modern malaria treatment uses specific antimalarial medicines according to the parasite and clinical situation.

A hydrogen fuel cell combines hydrogen and oxygen electrochemically to produce electricity. The main products are water and heat, so H₂O is the exhaust product.

Water has its maximum density at about 4°C. This anomalous expansion of water is important for aquatic ecosystems because ice floats while denser water remains below.