Question No : 15
Harmful bacteria in drinking water cannot be destroyed by
Question No : 16
Temporary hardness is due to the presence of
Question No : 17
The gas used in balloons in the place of hydrogen is
Question No : 18
Tincture iodine is a solution of
Question No : 19
Which of the following process involves removal of the elements of water?
Question No : 20
Which of the following types of water gives lather easily with soap?
Question No : 21
Ozone occurs in the upper layers of air in the atmosphere because