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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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.
Which of the following statement(s) about Acquired Immuno Deficiency Syndrome (AIDS) is/are correct?
1. AIDS is a congenital disease caused by a retrovirus known as Human Immuno deficiency Virus (HIV).
2. AIDS is characterised by a progressive decrease in the number of T-lymphocytes in the body of the infected person.
Select the correct answer using the code given below.
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.
Which of the following statement(s) is/are correct?
1. Saturated hydrocarbons are linked by only single bonds between the carbon atoms while unsaturated carbon compounds have double or triple bonds.
2. Saturated hydrocarbons generally give a clean flame while unsaturated carbon compounds give a yellow flame with lots of black smoke.
Select the correct answer using the code given below.
With reference to Pisces – a category of animals, consider the following statements:
1. Their skin is covered with scales and it has mucus glands on their skin.
2. They are aquatic animals that obtain oxygen dissolved in water by using gills.
3. Unlike humans, they are cold-blooded and have only three chambers in their heart.
Which of the statement(s) given above is/are correct?
Consider the following statements about Carbon dioxide (CO2):
1. Volcanic eruptions are a natural source of Carbon dioxide in the atmosphere.
2. Carbon dioxide is confined only to the tropospheric layer of the atmosphere.
3. Excess of Carbon dioxide in the air is removed by green plants by respiration.
Which of the statements given above is/are correct?
Consider the following statements:
1. Cold-blooded animals do not have the capacity to regulate their body temperature.
2. Amphibians are cold-blooded animals and reptiles are warm-blooded animals.
Which of the statements given above is/are correct?
Read the following statements carefully in the context of ‘particulate pollutants’?
1. Smoke particulates consist of gaseous or mixture of gaseous and liquid particles formed during combustion of organic matter.
2. Dust is composed of fine solid particles produced during crushing, grinding and attribution of solid materials.
3. Mists are produced by particles of spray liquids and by condensation of vapours in air.
4. Fumes are generally obtained by the condensation of vapours during sublimation, and boiling.
Which of the statements given above are correct?
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:
Manure contains large quantities of organic matter and also supplies small quantities of nutrients to the soil. In this context, consider the following statements:
1. The organic matter in manure helps in improving the soil structure.
2. It increases the water holding capacity in sandy soils.
3. It causes water logging in clayey soils.
Select the correct answer using the code given below: