General Science Mixed Quiz: Set 1

One newton is the force that gives a mass of one kilogram an acceleration of one metre per second squared, which follows directly from the equation force equals mass times acceleration.

At great heights the air is thin, so the atmospheric pressure acting on the body is much lower than at sea level.

Water is densest at about 4 degrees Celsius, and 4 plus 273 gives roughly 277 kelvin. Most liquids keep shrinking as they cool, but water behaves oddly: below 4 degrees Celsius it starts to expand again because its molecules begin forming the open, hexagonal pattern of ice.

Starlight has to cross many layers of air before it reaches the eye, and these layers keep changing in temperature and density, so their refractive index keeps changing too.

A healthy human ear can hear sound waves with frequencies from about 20 hertz to 20,000 hertz (20 kHz); this band is called the audible range.

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.

Zinc has atomic number 30, meaning every zinc atom has 30 protons in its nucleus. It is the last element of the first transition series in period 4 of the modern periodic table, with the electronic configuration [Ar] 3d10 4s2, and it is placed in group 12.

The name itself gives the formula: 'hexa' means six, so sulphur hexafluoride has one sulphur atom joined to six fluorine atoms, SF6.

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.

Galvanisation is the coating of iron or steel with a thin layer of zinc so that the iron underneath does not rust.

In diamond every carbon atom is joined to four other carbon atoms by strong covalent bonds. These bonds point towards the corners of a tetrahedron and build a rigid three-dimensional network that runs through the whole crystal.

Laughing gas is nitrous oxide, N2O, a colourless gas with a faintly sweet smell that makes people giggle and feel light-headed when they breathe it in.

Mature red blood cells, or erythrocytes, lose their nucleus before they enter the blood. Losing the nucleus, and the mitochondria too, leaves more room for haemoglobin, the iron-rich protein that carries oxygen, and gives the cell its flexible biconcave disc shape, which lets it squeeze through narrow capillaries.

Air always moves from a region of higher pressure to one of lower pressure, so it flows out of the lungs only when the pressure inside them rises above that of the outside air.

A person with AB positive blood can receive red cells from every ABO and Rh group, so AB+ is called the universal recipient.

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.

Beriberi is caused by a lack of thiamine, which is vitamin B1. Thiamine helps the body turn carbohydrates into energy and keeps nerves and the heart working, so its shortage weakens muscles and nerves (dry beriberi) or causes swelling and heart failure (wet beriberi).

Of the three, only citrus canker is caused by bacteria; rust of wheat is caused by a fungus and yellow vein mosaic of bhindi by a virus.

It is the main growth inhibitor among plant hormones and works against the growth promoters.

All three are genetic disorders, caused by changes in genes or chromosomes and passed on through birth, not by germs.