All automobiles and fuel $-$petrol and diesel were to have met the Euro $III$ emission specifications in some cities from $1$ April $2005$ and have to meet the Euro$-IV$ norms by:
In the textbook you came across Three Mile Island and Chernobyl disasters associated with accidental leakage of radioactive wastes. In India we had Bhopal gas tragedy. It is associated with which of the following?
Waste water from domestic and industrial processes
B
Agricultural pollution
C
Oil pollution
✓
All of the above
Answer
Correct option: D.
All of the above
The most significant sources of water pollution are wastewater$($sewage$),$ agricultural pollution, Oil pollution, radioactive substances, water body dumping.
Reducing reforestation, increasing the use of fossil fuel.
B
Increasing deforestation, slowing down the growth of human population.
C
Increasing deforestation, reducing efficiency of energy usage.
✓
Reducing deforestation, cutting down use of fossil fuel.
Answer
Correct option: D.
Reducing deforestation, cutting down use of fossil fuel.
Global warming is the biggest challenge for the developing countries like India. The rapid increase in human population and the increased levels of pollution are the major contributors of global warming.
The percentage of heat$-$trapping carbon dioxide $(\mathrm{CO}_2)$ increases due to the burning of fossil fuels to generate electricity, fuel our cars, and heat our homes.
Deforestation also increases the concentration of carbon dioxide in the atmosphere.
The-amount of $\mathrm{O}_2$ utilised by organisms in water.
B
The amount of $\mathrm{O}_2$ utilised by micro organisms for decomposition.
✓
The total amount of $\mathrm{O}_2$ present in water.
D
All of the above.
Answer
Correct option: C.
The total amount of $\mathrm{O}_2$ present in water.
Biochemical oxygen demand $\text{(BOD)}$ is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period.
Micro$-$organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures.
$\mathrm{CO}_2$ is mixed in large amount in water.
Answer
Correct option: A.
Of its bad smell.
Sewage discharge in water bodies leads to organic loading or occurrence of excess organic matter inside water body.
Its putrefaction decreases dissolved oxygen leading to competition for oxygen among fishes. Also blue green algae bloom and increase in number and release toxins. Both toxicity and decreased oxygen level kill aquatic animals, like fishes.
A sewage treatment process in which a portion of the decomposer bacteria present in the waste is recycled into the beginning of the process, is called.