General Science GK Questions with Answers – Page 125

A ray that passes through the optical centre of a thin lens comes out in the same direction, without any bending.

Red cabbage is a natural acid-base indicator, methyl orange is a synthetic acid-base indicator, and onion and clove are olfactory indicators.

The d-block occupies the middle of the modern periodic table, groups 3 to 12, and its members are also called transition elements.

A red blood cell is a biconcave disc, thin in the middle and thick at the edge, not an amoeboid cell.

Mercury (Hg) belongs to group 12, not group 11. Group 11 of the modern periodic table holds copper (Cu, atomic number 29), silver (Ag, 47) and gold (Au, 79).

Platelets are the tiny cell fragments that rush to a cut and start the clot. They are also called thrombocytes and are made in the bone marrow from large cells called megakaryocytes.

A qubit, short for quantum bit, is the basic unit of information in a quantum computer.

The cooking temperature is set by the pressure inside the cooker, and that pressure is fixed by the weight sitting on the vent and the area of the hole under it.

Water is called the universal solvent because its molecule is polar: the oxygen end carries a partial negative charge and the two hydrogen ends carry partial positive charges.

The pineal gland, a small pine-cone-shaped gland deep in the brain, secretes melatonin. Melatonin controls the body's day-night rhythm, called the circadian rhythm, and helps regulate sleep.

Thiamin (thiamine) is vitamin B1, a water-soluble vitamin that helps the body turn carbohydrates into energy and keeps the nerves and heart working well.

Milk of magnesia is a milky white suspension of magnesium hydroxide, Mg(OH)2, in water. It is a mild base, so it neutralises the extra hydrochloric acid in the stomach that causes acidity and heartburn; the reaction gives magnesium chloride and water.

In 1831 the British scientist Michael Faraday showed that a changing magnetic field produces an electric current in a nearby coil.

Calcium oxychloride (CaOCl2) is bleaching powder, and the chlorine it releases removes colour from cotton and linen in the textile industry.

One ampere is the current that flows when one coulomb of charge passes a point in a circuit in one second.

The symbol of potassium is K, from its Latin name kalium; Po is the symbol of polonium, the radioactive element discovered by Marie Curie in 1898 and named after Poland.

Its chemical name is sodium hydrogen carbonate and its formula is NaHCO3. It is a mild, non-corrosive base made by the Solvay process, in which brine is treated with ammonia and carbon dioxide.

Both pairs are wrong. Amyloplasts store starch, a carbohydrate, and aleuroplasts store proteins; oils and fats are stored by elaioplasts.

Ammonia is NH3, so one nitrogen atom of mass 14 is joined to three hydrogen atoms of mass 1 each, giving 14: 3 by mass.

This is Kirchhoff's first law, the current law or junction rule, which he stated in 1845. It says the total current entering a junction equals the total current leaving it, because charge cannot pile up or vanish at a point.