Exams › JEE Main › Chemistry

When copper is left in moist air for a long time, it develops a green coating because of:

1. a layer of cupric oxide forming on the copper surface
2. a layer of basic copper carbonate forming on the copper surface
3. a layer of cupric hydroxide forming on the copper surface
4. a layer of basic copper sulphate forming on the metal surface

Correct answer: a layer of basic copper carbonate forming on the copper surface

Solution

Copper reacts with moisture and carbon dioxide in the air over time, leading to the formation of basic copper carbonate, which gives the characteristic green patina. This process is a result of copper's corrosion in the presence of these elements.

Related JEE Main Chemistry questions

• Why is chlorine commonly added during water treatment?
• Which of the following is classified as a primary pollutant?
• In automobile exhaust, which of the following are considered harmful pollutants? (i) N2 (ii) CO (iii) CH4 (iv) Oxides of nitrogen
• If rainfall occurs together with a thunderstorm, the pH of the rainwater collected will be
• Photochemical smog is most likely to form during which condition?
• The B.O.D. (biochemical oxygen demand) test is used to assess the level of

⚔️ Practice JEE Main Chemistry free + battle 1v1 →