Deep sea divers have been using the compressed air containing \({ N }_{ 2 }\) in addition to \({ O }_{ 2 }\) for breathing. When the sea diver breathes in compressed air at a depth, more \({ N }_{ 2 }\) dissolves in the blood and other body fluids than would dissolve at the surface because the pressure at the depth is far greater than surface atmospheric pressure. When the diver comes towards the surface, the pressure decreases and  \({ N }_{ 2 }\) comes out of the body quickly forming bubbles in the blood stream which restrict blood flow and affect the transmission of nerve impulses. This results into a condition called 'the bends' which is dangerous and painful. To avoid this condition, professionals now use air diluted with helium. As a student of chemistry, can you analyse as to why helium is used?

Manu and his father went to a shop to purchase a battery for their inverter. The shopkeeper showed them two types of batteries, one with lead plates and the other with cadmium plates. The battery with cadmium plates was more expensive than the lead battery. Manu's father wanted to purchase lead battery as it was cheaper.
After reading the above passage answer the following questions:
(a) As a student of chemistry, why would you suggest Manu's father buy the expensive cadmium plate battery. Give two reasons.
(b) What are the values associated with the above decision?

It is desired to produce ammonia gas from nitrogen and hydrogen according to the reaction:
\({ N }_{ 2 }(g)+3H_{ 2 }(g)\rightleftharpoons 2NH_{ 3 }(g)+Heat\)
Above reaction is exothermic and therefore, favored by low temperature. As a student of chemistry,which temperature would you suggest 350k or 750 k? Justify 

Nitrogen fertilizers are commonly used to promote the growth of plants and boost the crop yield.As a student of chemistry,can you suggest a farmer whether he should use excess nitrogen fertilizers to get maximum yield or not?

Trichloromethane or chloroform is a colorless oily liquid with a peculiar smell.It is sparingly soluble in water.The vapor when enhaled cause unconsciousness and therefore, it is used as an anesthetic.
Answer the following questions:
(i) What happens when chloroform is not protected from oxygen during its storage?
(ii) Why is the use of chloroform as an anesthetic has been reduced?