Question

Describe the threat to the beauty of the Taj Mahal.

Answer 1

Hint: Taj Mahal, the historical monument in India is made up of marbles. When marbles are exposed to chemicals, it corrodes. Marble is made up of calcium salt which reacts with chemicals such as sulphuric acid and nitric acid and gets converted to a salt of calcium which does not have the properties of marble.

Complete step by step solution:
-Taj Mahal is an ivory-marble monument situated on the southern banks of Yamuna River in Agra. This area has numerous industries nearby. All these industries, they release large amounts of chemicals into the air and also release soot particles. Large quantities of oxides of nitrogen and sulphur are emitted into the sky. Mainly an industry in Mathura called the Mathura Oil refinery releases acid fumes into the air. The acidic gases are sulphur dioxide, sulphur trioxide and nitrogen dioxide.
-Now let us discuss how the emission of such gases affects Taj Mahal. The acidic gases mentioned above can react with water vapour present in the atmosphere. Or when it rains, it reacts with the rain droplets and it converts to sulphuric acid and nitric acid. When it rains, they are washed down to earth. Now Taj Mahal is made up of marble. The main component of marble is calcium carbonate. So, sulphuric acid and nitric acid react with calcium carbonate to form calcium sulphate and calcium nitrate, respectively.
\[\underset{marble}{\mathop{CaC{{O}_{3}}}}\,+\underset{acidrain}{\mathop{{{H}_{2}}S{{O}_{4}}}}\,\to CaS{{O}_{4}}+C{{O}_{2}}+{{H}_{2}}O\]
\[\underset{marble}{\mathop{CaC{{O}_{3}}}}\,+\underset{acidrain}{\mathop{HN{{O}_{3}}}}\,\to Ca{{(N{{O}_{3}})}_{2}}+C{{O}_{2}}+{{H}_{2}}O\]
The salts calcium nitrate and calcium sulphate can dissolve in water. Due to this, the marble of Taj Mahal will get corroded and will lose its lustre by its reaction with the acidic gases present in the atmosphere or with this acid rain. Usually these reactions are very slow and it takes a very long time to damage monuments and buildings.
Thus, the threat to beauty of Taj Mahal is due to toxic emissions from the nearby industries which leads to acid rain and corrodes the marble of Taj Mahal.

Note: Corrosion of marble by acid rain is called ‘Marble cancer’. The marble is corroded mainly by sulphuric acid and nitric acid. Most buildings and statues made up of marble undergo marble cancer and cause its destruction.