Question

A lake is found fully covered with algae and scum. The water from this lake is used by people living nearby it for their household purposes. It is also found that many children are suffering from diarrhea and muscle cramps. As a precaution the doctor advises them not to drink water from the lake, and if at all they use it, it should be boiled and cooled.

Hydrogen gas is an excellent fuel. It has a high calorific value and produces only water as the product of combustion. It is considered to be a potentially important, non-polluting energy source of the future. Hydrogen is labelled with different 'colours' based on the method by which it is produced, as given below: - green hydrogen: manufacturing process does not produce carbon dioxide - blue hydrogen: manufacturing process produces carbon dioxide but it is separated and stored - grey hydrogen: manufacturing process produces carbon dioxide which is released into the air Hydrogen is labelled 'brown' if the manufacturing process releases both carbon dioxide and carbon monoxide to the air. In what way is the manufacturing process of brown hydrogen WORSE than that of grey hydrogen for the environment?

Hydrogen gas is an excellent fuel. It has a high calorific value and produces only water as the product of combustion. It is considered to be a potentially important, non-polluting energy source of the future. Hydrogen is labelled with different 'colours' based on the method by which it is produced, as given below: - green hydrogen: manufacturing process does not produce carbon dioxide - blue hydrogen: manufacturing process produces carbon dioxide but it is separated and stored - grey hydrogen: manufacturing process produces carbon dioxide which is released into the air The widespread use of which type(s) of hydrogen will help in containing global warming?

Which among the following is/are an indication of high contamination in a river? (i) low pH of the river water (ii) existence of diverse life forms in the river (iii) presence of mercury ions in the water (iv) presence of E.coli bacteria in water Choose the correct option from the following: