General Science Previous Year Questions (PYQ) with Answers – Page 2

Cooking soda, also called baking soda, is sodium hydrogen carbonate, also known as sodium bicarbonate. It is a mild base made from one sodium, one hydrogen, one carbon and three oxygen atoms.

Black copper(II) oxide reacts with dilute hydrochloric acid to form copper(II) chloride and water, and the solution turns blue-green because of the copper(II) ions.

Marble, chalk and limestone are all made of the same compound, calcium carbonate, with the formula CaCO3. They differ only in how they were formed.

Metal blocks X-rays far more strongly than body tissue, so it spoils the picture. An X-ray image is a shadow picture.

A rod standing upright on one end falls over at the slightest push, because its centre of gravity is high and its base is tiny.

The magnetic force on a moving charge is F = q(v × B), and only an upward field turns a westward-moving positive charge towards the north.

Light, small and dry pollen is a feature of wind-pollinated plants, not of plants that depend on insects. Insect-pollinated (entomophilous) flowers have to attract a visitor and then make the pollen travel on its body.

Cardiac muscle is a muscular tissue, not a connective tissue; it is the striated, branched, involuntary muscle that makes up the wall of the heart and contracts rhythmically for life.

Ribosomes make proteins, a job every living cell must do, so they are present in both prokaryotic and eukaryotic cells.

The force gives the car an extra 15 m/s, which is 54 km/h, and 40 + 54 = 94 km/h. By Newton's second law, acceleration a = F/m = 1000 N ÷ 800 kg = 1.25 m/s².

A typical flower has four whorls arranged on the thalamus: sepals on the outside, then petals, then stamens, and carpels at the centre.

The opening of the pulmonary artery from the right ventricle is guarded by the pulmonary semilunar valve, which stops blood from flowing back into the ventricle when it relaxes.

In bryophytes the main, independent plant body is the haploid gametophyte, while the diploid sporophyte stays attached to it and depends on it for food.

Heat produced per unit time is the power, and with a fixed battery voltage the power is P = V²/R. So the circuit gives the most heat when its total resistance is the smallest, and the smallest possible resistance comes from joining all three resistors in parallel.

Tidal volume, the air breathed in or out in one normal quiet breath, is only about 500 millilitres in a healthy adult, the smallest of the four volumes listed.

Frogs and most fishes release their eggs and sperm into water, where fertilisation takes place outside the female's body. In external fertilisation, a large number of eggs and sperm are shed together, because many are lost to currents and predators.

The nucellus is the mass of tissue inside the ovule whose cells carry stored food, and the embryo sac develops within it.

The corpus callosum is a thick band of nerve fibres that joins the two cerebral hemispheres, so it belongs to the forebrain, not the hindbrain.

The bronchi only carry air between the windpipe and the lungs; their walls are too thick for oxygen and carbon dioxide to pass into the blood, so no gas exchange happens there.

All four are parts of the two complex permanent tissues of plants: tracheids and vessels belong to xylem, while sieve tubes and companion cells belong to phloem.