Consider the following statements about ‘Biochemical Oxygen Demand’ (BOD):
1. It is the amount of oxygen required by bacteria to break down the organic matter present in a certain volume of a sample of water.
2. Highly polluted water have BOD value of less than 5 ppm.
Which of the statements given above is/are correct?
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Read the following statements carefully and select the correct answer from codes given below:
1. Working of electric motors involves the electric effect of electric current.
2. Working of electric generators involves the magnetic effect of moving magnets.
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:
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.
Select the correct answer using the code given below.
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 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?
Consider the following statements:
1.
Consider the following statements:
1. Anti-viral medicines are harder to make as viruses have biochemical mechanisms of their own.
2. Anti-bacterial medicines target both bacteria and fungi.
Which of the statement(s) given above is/are correct?
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?
The ‘scattering of light’ is responsible for which of the following phenomena in nature?
1. Tyndall effect.
2. Colour of water in deep sea.
3. Blue colour of the sky.
4. Rainbow formation.
Select the correct answer using the code given below.
Consider the following statements:
1. The direction of current is taken opposite to the direction of flow of electrons.
2. Resistance is a property of a conductor that generates heat in the electrical circuit.
3. The SI unit of electric current is Amperes.
Select the correct answer using the code given below: