General Science Questions and Answers

Answer: B

The human body has 24 ribs - twelve pairs.

The first seven pairs are true ribs, joined directly to the sternum by cartilage; the next three are false ribs, attached to the cartilage above; and the last two are floating ribs, attached only to the vertebrae.

Answer: D

Coffee was the earliest plantation crop introduced in India.

Tradition holds that Baba Budan brought seven beans from Yemen in the seventeenth century and planted them in the hills of Chikmagalur in Karnataka. Tea came much later, in the 1830s, under the British.

Answer: A

Hydrogen is the element common to all acids. An acid is defined as a substance that releases hydrogen ions (H⁺) in water.

Hydrochloric acid gives HCl → H⁺ + Cl⁻, sulphuric acid gives two hydrogen ions, and it is the concentration of those ions that the pH scale measures.

Answer: B

A lactometer tests the purity of milk. It is a hydrometer calibrated for milk, and measures specific gravity - normally between 1.028 and 1.034.

Adding water lowers the reading, so the instrument detects dilution, though it will not detect skimming, which raises the density instead.

Answer: C

A chronometer measures time - a clock accurate enough to keep time at sea.

John Harrison's marine chronometer, perfected in the 1760s, solved the longitude problem: comparing local noon with the time at a reference meridian gives longitude directly.

Answer: D

Tetraethyl lead was used as a petrol additive, raising the octane rating and preventing engine knock.

It was phased out worldwide because the lead in the exhaust is a cumulative poison that damages the nervous system, especially in children. India completed the switch to unleaded petrol in 2000.

Answer: B

Paper is made chiefly from wood. The wood is pulped - mechanically or with chemicals that dissolve the lignin - to free the cellulose fibres, which are then matted, pressed and dried into sheets.

Softwoods such as pine give long fibres and strength; hardwoods give shorter fibres and a smoother surface.

Answer: B

Heparin is the natural anticoagulant of the blood. It is produced by mast cells and by the basophils, and it works by activating antithrombin, which then inactivates thrombin.

It is what keeps blood fluid inside the vessels. Hirudin is the anticoagulant of the leech, not of human blood.

Answer: D

Tulsi, holy basil, is called the herbal Indian doctor.

It is the most widely used plant in Ayurveda, taken for coughs, fever and digestive complaints, and is grown in the courtyard of many Indian homes.

Answer: A

Collagen is the major ingredient of leather - the fibrous protein of animal skin.

Tanning cross-links its fibres so they no longer rot or dry hard. Collagen is also the commonest protein in the body, forming the framework of skin, tendon, bone and cartilage.