Clothes keep us warm in winter because they : (1) supply heat (2) do not radiate heat (3) prevent air from contacting the body (4) prevent the heat of the body from escaping Answer: (4) It is just because woollen clothes have fibres and between those fibres air is trapped which reduces heat loss. Air reduces … Read more
In a refrigerator what produces the cooling? (1) The ice which deposits on the freezer (2) The sudden expansion of a compressed gas (3) The evaporation of a volatile liquid (4) None of these Answer: (4) Basically, a refrigeration system consists of devices that compress and expand refrigerant gas. When refrigerant gas is compressed it expels … Read more
Why are we able to hear short wave broadcasts better than longwave broadcasts? (1) Short waves are more energetic than long waves. (2) Short waves are unaffected by atmospheric disturbances. (3) Short wave broadcasts are made by nearby radio stations. (4) By convention, short waves are meant for long distances, whereas long waves are reserved … Read more
When the barometer reading dips suddenly, it is an indication of (1) Hot weather (2) Calm weather (3) Storm (4) Dry weather Answer: (3) Sudden and great fluctuations of the barometer at any time of the year indicate unsettled weather for several days, perhaps a fortnight. If the barometer falls two or three-tenths of an inch … Read more
Good conductor of electricity is (1) dry air (2) paper (3) kerosene (4) graphite Answer: (4) Graphite has a tendency to behave very much like metal because the carbon molecules arrange themselves into a lattice structure. The crystal lattice is the same orientation that metal forms, and it allows the free movement of electrons, making it … Read more
Which of the following is a non-renewable source of energy? (1) Biogas (2) Solar (3) Wind (4) Coal Answer: (4) A non-renewable resource is a natural resource that cannot be reproduced, grown, generated, or used on a scale that can sustain its consumption rate. So, coal is a non-renewable source of energy. Once it is depleted, … Read more
The term ‘equinox’ means (1) The path which the Earth takes around the Sun (2) The axis of the Earth around which it rotates (3) When the day and night are of equal duration (4) The time when the Sun seems to be going round and round in the sky in the Arctic but does … Read more
Heat from the Sun reaches the Earth by (1) Reflection (2) Conduction (3) Radiation (4) Convection Answer: (3) The radiation (light, heat, etc.) travels through the intervening 150, 000,000 kilometres in 8 minutes. Radiation is a process in which energetic particles or energetic waves travel through a vacuum, or through matter-containing media that are not required … Read more
Solar energy is converted into chemical energy during (1) Transpiration (2) Photosynthesis (3) Diffusion (4) Osmosis Answer: (2) In photosynthesis, solar energy is converted to chemical energy. The chemical energy is stored in the form of glucose (sugar). Carbon dioxide, water, and sunlight are used to produce glucose, oxygen, and water. Photosynthesis is a process used … Read more
In which of the following cases, kinetic energy is being used in performing work? (1) Paddling the bicycle to cover a distance (2) Driving a car to cover a distance (3) Windmill grinding wheat grain (4) Rowing a boat in the lake Answer: (2) The work done on any object goes into changing the kinetic energy … Read more