Rana purchased a monumnet made of copper. It turned green after some time. As a student of chemistry, how would you explain this?

Concrete has been most widely used as a building material. It is reinforced by rods which make it hard and stronger. However, it has been noticed that some old buildings are showing signs of weakness and cracks. As a student of chemistry how would yu analyse this shocking situation? is there any method to protect these buildings from further damage?

Plants usually show better growth when ammonium sulphate is added to the soil. How would you explain this behaviour?

Raghav was returning with his family from a marriage party. On the way, a traffic policeman stopped their car. He asked Raghav’s father who was driving the car to exhale his breath into an instrument to check whether he has drunk or not. After checking from the instrument, he allowed them to go. As a student of chemistry: Can you explain the theory behind this test ?

A capactiro of capacitance C is being charged by connecting it across a d.c. source along with an ammeter. Will the ammeter show a momentary deflection during the process of charging? If so , how would you explain the momentary deflextion and the resulting continuity of current int he circuit? Write the expression for current inside the capcitor.

In the North East region of India, during the process of Jhum cultivation, forests are cleared by burning and left for regrowth after a year of cultivation. How would you explain the regrowth of forest in ecological term?

Deep sea divers have been using the compressed air containing N_2 in addition to O_2 for breathing. When the sea divers breathes in compressed air at a depth, more N_2 dissolves in the blood and other body fluids than would dissolved at the surface because the pressure at the depth is far greater than surface atmospherice p ressure. when the diver comes towards the surface, the pressure decreases and N_2 comes out of the body quickly forming bubbles in the stream which restrict blood flow and affect the transmission of nerve impuses. 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?

The blue colour of crystals of a substance changed on heating in a closed test tube but the colour was regained after some time on cooling. Name the substance and write its chemical formula. Explain the phenomenon involved.

When in the blue solution of copper sulphate, Zinc srtip is dipped, after some time colour changes to: