UPSC Civil Services Model Paper 5

The survival of living organisms is based on a very slight change in pH range.
The working of the human body takes place within the range of 7.0 to 7.8 .
Hence statement 1 is correct .
The human body can not sustain the high variation of pH levels.
pH is called as power of Hydrogen , that is how much water or acid is present in any living organism or chemical at a particular point of time with different functioning of different organs of the body.
When sulfur dioxide (SO2)andnitrogen oxide (NOx) are discharged in the atmosphere and travel by wind and air current , the resultant rain is called Acid rain (H2SO4).
At the time of acid rain, the pH level of rain is less than 5.6.
Hence statement 2 is correct .
The main originators of SO2and NOx are the following :
Pollution by heavy motor vehicles.
Igniting of fossil fuels for generating electricity.
Pollution from industries and oil refineries.