1. Which of the following statement(s) in the context of ‘Human Eye’ is/are NOT correct?
1. Most of the refraction of the light rays entering the eye occurs at the outer surface of the crystalline lens.
2. Iris is a dark muscular diaphragm that controls the size of the pupil.
3. Pupil regulates and controls the amount of light entering the eye.
4. Retina is a delicate membrane having enormous number of light-sensitive cells.
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Consider the following statements about ‘Photochemical Smog’:
1. It is a phenomenon of cool humid climate.
2. It occurs when sunlight acts on unburnt hydrocarbons and nitrogen oxides.
3. Ozone in photochemical smog is responsible for the haze.
Which of the statements given above is/are correct?
Some countries now use alcohol as an additive in petrol. In context of this, consider the following statements:
1. Addition of alcohol increases the burning efficiency of petrol and reduces knocking.
2. Petrol added with small quantities of alcohol becomes more stable and doesn’t become too hot in warm areas or too cold in freezing temperatures.
3. Alcohol is a cleaner fuel which gives rise to only carbon dioxide and water on burning in sufficient oxygen.
Which of the statements given above is the correct reason for using alcohol as an additive in petrol?
Which of the following statement(s) is/are correct?
1. The B-lymphocytes in human body produce an army of proteins in response to pathogens into our blood to fight with them.
2. The T-lymphocytes mediate cell-mediated immunity (CMI) which is responsible for the graft (transplanted body-part) rejection.
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In the context of ‘immunity’ in human body, which of the following statements is/are correct?
1. Skin on our body is an example of innate immunity.
2. Acquired immunity is characterised by memory.
3. Injecting the microbes deliberately during immunisation induce passive immunity.
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If an opaque object on the path of light becomes very small, light has a tendency to bend around it and not walk in a straight line. This effect is known as:
Consider the following statements:
1. Some substances like carbon dioxide or oxygen can move across the cell membrane by a process called Osmosis.
2. In the cell’s external environment, the concentration of carbon dioxide is low as compared to that inside the cell.
Which of the statement(s) given above is/are correct?
Compass is an important tool used for navigation since old days. In this context, consider the following statements:
1. The compass needle is a magnet which align itself in a particular direction.
2. The compass needle always points towards the magnetic south pole of the earth.
Which of the statement(s) given above is/are correct?
Which of the following phenomena are caused due to ‘atmospheric refraction’?
1. Flickering of objects seen through a turbulent stream of hot air rising above a fire.
2. The reddening of the sun at sunrise and the sunset.
3. The apparent flattening of the Sun’s disc at sunrise and sunset.
4. The Sun is visible to us about 2 minutes before the actual sunrise, and about 2 minutes after the actual sunset.
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Consider the following statements about ‘Acid Rain’:
1. Oxides of sulphur and nitrogen are major contributors to acid rain.
2. Acid rain is good for agriculture as it provides nitrogen for the growth of plants.
3. When acid rain flows into the river, it increases the pH level of river water.
Which of the statements given above is/are correct?
Consider the following statements about ‘rainbow’:
1. It is caused by dispersion of sunlight by tiny water droplets present in the atmosphere.
2. A rainbow is always formed in a direction opposite to that of the Sun.
Which of the statements given above is/are correct?