General Science Mixed Quiz: Set 204

Work is negative when the force acts opposite to the displacement, because the angle between them is then 180°. Work done is W = F S cos θ, where θ is the angle between the force and the displacement.

The correct answer is B, measles, a viral disease spread by droplets, which is why it is prevented by vaccination and not treated with antibiotics.

A plane mirror always forms an upright image of the same size as the object, and the image cannot be caught on a screen.

The correct answer is B, the oral polio vaccine, which contains live poliovirus weakened so that it can multiply in the gut and raise immunity without causing the disease; it is the vaccine given as two drops in the pulse polio rounds.

In a given medium under the same conditions, sounds of all frequencies travel at the same speed; the speed depends on the medium, not on the pitch.

In 1983 the American company Eli Lilly put the DNA sequences of the A and B chains of human insulin into Escherichia coli, produced the two chains separately and joined them by disulphide bonds to make a hormone identical to the human one; it was sold as Humulin, the first…

Seen from the east end, the current flows away from the observer, and by the right-hand thumb rule the field lines around it are clockwise circles in a plane perpendicular to the wire.

Clove is the unopened flower bud of Syzygium aromaticum, picked before it blooms and dried, and it is grown in India chiefly in Kerala, Tamil Nadu and the Andaman and Nicobar Islands.

Turmeric is a natural indicator: soap is basic and turns the yellow stain reddish brown, and rinsing with plenty of water removes the soap so the stain turns yellow again.

It is a spiral galaxy of a few hundred billion stars, and the solar system lies in one of its spiral arms, far from the centre, which is why we see the galaxy edge on as a milky band across the night sky.

Zinc gives up electrons more readily than iron, so it corrodes first and keeps the iron safe. Coating iron or steel with a thin layer of zinc is called galvanisation.

A cosmic ray physicist who founded the Physical Research Laboratory at Ahmedabad, he persuaded the government that a poor country needed space technology for communication, weather and education, set up the rocket launching station at Thumba and built the organisation that became the Indian Space Research Organisation.

Sodium carbonate, called washing soda in its hydrated form Na₂CO₃·10H₂O, removes both temporary and permanent hardness of water. Hard water contains dissolved calcium and magnesium salts, which stop soap from lathering.

The word itself means naked seed: the ovules are not enclosed in an ovary, so after fertilisation the seeds lie exposed on the surface of the scales of a cone and no fruit is formed.

Ribosomes are the only one of these found in prokaryotic cells such as bacteria, because they are not enclosed by a membrane.

Carbon dioxide reacts with lime water, a solution of calcium hydroxide, to form insoluble calcium carbonate, whose fine white particles make the liquid look milky; if more of the gas is passed the milkiness disappears as soluble calcium bicarbonate is formed, and that second step is often the harder half…

A mature mammalian red blood cell has no nucleus, ribosomes or mitochondria, so it can neither make proteins nor divide.

Each of them is made of two simple sugar units joined together, which is exactly what a disaccharide is. Carbohydrates are grouped by the number of sugar units they contain.

It is caused by the bacterium Vibrio cholerae, which spreads through food and water polluted with human faeces. The bacterium was identified by Robert Koch in 1883.

These are the only two elements that are liquid at standard room temperature and pressure: mercury is a metal and bromine is a non-metal.