Weeds are unwanted plants in a cultivated field. In this context, consider the following statements:
1. The weeds compete for food, space and light.
2. Weeds are responsible for affecting the growth of the crop.
3. Timely sowing of crops and crop rotation help in weed control.
Which of the statement(s) given above is/are correct?
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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?
Consider the following statements about the ‘scattering of light’:
1. Very fine particles scatter mainly blue light while particles of larger size scatter light of longer wavelengths.
2. If the size of the scattering particles is large enough, then, the scattered light may even appear white.
Which of the statements given above is/are correct?
The parasitic nutritive strategy, by which some organisms derive nutrition from plants or animals without killing them, is used by which of the following organisms?
1. Cuscuta (amar-bel)
2. Ticks
3. Bread moulds
4. Tape-worms
Select the correct answer using the code given below.
Consider the following statements:
1. Exchange of gases in plants occurs not only across the surface of leaves but also across the surface of stems and roots.
2. Plant close its pores known as the Stomata, when they do not need carbon dioxide for photosynthesis.
3. Guard cells present in plants are responsible for controlling the movement of water in them.
Which of the statements given above is/are correct?
Consider the following statements:
1. The motion of the moon around the earth is due to the centrifugal force.
2. The moon rotates around its axis due to the gravitational pull of the earth.
Which of the statement(s) given above is/are NOT correct?
Consider the following statements:
1. The aperture of the pupil of a human eye can be changed with the help of the ciliary muscles.
2. The curvature of human eye cannot be changed, because the lens of a human eye is fixed.
Which of the statements given above is/are correct?
Consider the following statements:
1. Methanol is a low carbon, hydrogen carrier fuel produced from high ash coal, CO2 from thermal power plants and natural gas.
2. ‘Methanol Economy’ programme has been launched with the objective of reducing India's oil import bill and greenhouse gas (GHG) emissions.
3. The Methanol Economy programme has been launched by the Ministry of Petroleum and Natural Gas.
Which of the statements given above is/are correct?
Read the following statements carefully:
1. Vector-borne diseases are caused by parasites, viruses and bacteria.
2. Skin infections are generally caused by different kinds of fungi.
3. Elephantiasis is a disease caused by different species of worms.
Which of the statement(s) given above is/are correct?
Which among the following are the characteristic features of birds?
1. They are cold-blooded animals.
2. They lay eggs.
3. Two forelimbs are modified for flight.
4. They breathe through lungs.
Select the correct answer using the code given below:
Consider the following statements with reference to the ‘magnetic field’ of a bar magnet:
1. Magnetic field is a quantity that has both direction and magnitude.
2. Inside the magnet, the direction of field lines is from its south pole to north pole.
3. Magnetic field-lines of two different magnets can intersect each other.
Which of the statement(s) given above is/are correct?