Question

The phenomenon marble cancer is due to:
(A) Soot particles
(B) CFCs
(C) Fog
(D) Acid rain

Answer 1

Hint:Marble cancer occurs due to a type of reaction of marble with a chemical compound in which the reaction is called corrosion. Sulphur dioxide, nitrogen dioxide are the gases that are responsible for marble cancer.

Complete step by step answer:
- Marble cancer is nothing but corrosion of marble material. Now, let’s see what is responsible for its corrosion.
- Sulphur dioxide and nitrogen oxides ($N{{O}_{x}}$ ) are emitted into the atmosphere and transported by wind and air currents. These react with water, oxygen and other chemicals to form sulphuric and nitric acids. They then get mixed with water and other compounds before falling to the ground.
- So, we can say that acid rain is a form of precipitation with acidic components, such as sulphuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms. This can include rain, snow, fog or dust which is acidic in nature.
- Here, we should note that acid rain results when sulphurous, sulphuric, and nitric acids in polluted air and rain react with the calcite in marble and limestone, the calcite dissolves. We can see roughened surfaces or removal of material or loss of carved details in the areas of buildings or architecture that is exposed. Stone surface material may be lost all over or only in spots that are more reactive. We might expect that sheltered areas of stone buildings and monuments would not be affected by acid precipitation.
- We can say that sheltered areas on limestone and marble buildings and monuments show blackened crusts that have peeled off in some places, revealing crumbling stone beneath. This black crust is primarily composed of gypsum, a mineral that forms from the reaction between calcite, water, and sulphuric acid. We should note that gypsum is soluble in water; although it can form anywhere on carbonate stone surfaces that are exposed to sulphur dioxide, it is usually washed away. It remains stuck only on the surfaces that are protected from rain.
So, from the above discussion we can say that marbles get corroded when kept in open for a long time, because of acid rain. We know that marble is made up of calcium carbonate. And when acid present in rain reacts with calcium carbonate, this results in the corrosion. And this is known as Marble cancer.

So option D is correct.

Note:
Remember that CFCs are responsible for global warming and it cannot react with marbles, so it does not have any relation with marble corrosion. Remember that nitrogen oxides and sulphur dioxides are not directly responsible (means they do not react with marble) for marble corrosion but the acids formed by their reaction with water are directly responsible for marble corrosion.