General Science Previous Year Questions (PYQ) with Answers – Page 96

Human beings are ureotelic, which means the main nitrogen waste they pass out is urea. When the body breaks down extra amino acids, ammonia is produced, and ammonia is highly poisonous even in small amounts.

A rise of 27°C is a rise of 27 K, because one degree Celsius and one kelvin are exactly the same size.

In the core of the Sun, at a temperature of about fifteen million kelvin, four hydrogen nuclei combine through the proton-proton chain to form one helium nucleus.

Potassium permanganate is a neutral compound, so the oxidation numbers of all its atoms must add up to zero. Potassium, an alkali metal, is always +1, and each of the four oxygen atoms is -2, giving the oxygens a total of -8.

A microphone is a transducer: sound waves strike a thin diaphragm, the diaphragm vibrates, and that mechanical vibration is turned into a varying electric signal.

At sunset the Sun is close to the horizon, so its light travels through a much thicker layer of atmosphere before it reaches the eye.

In an ion exchange plant the water passes through a cation resin, which takes up the calcium and magnesium ions, and then through an anion resin, which takes up the sulphate, chloride and bicarbonate ions; because the hardness-causing ions are actually taken out of the water, the hardness can be…

A harvested fruit is still a living tissue that keeps respiring, using up its own sugars and acids and giving off heat, carbon dioxide and ethylene.

Hooke's law holds only as far as the limit of proportionality, and that limit is either equal to or lower than the elastic limit, so statements 1 and 4 are the correct pair.

Photosynthesis makes carbohydrate and gives out oxygen, and of the four choices here only oxygen is something the plant produces.

In graphite each carbon atom is joined to only three other carbon atoms in flat hexagonal layers, so the fourth valence electron of every atom is not used in bonding and can move freely along the layer.