Question

Where should an object be placed from a converging lens of focal length 20cm,
so as to obtain a real magnified image​

Answer 1

Answer:

Copper is comparatively less reactive but reacts with reagents like oxygen and water in atmosphere in a slow time. Also carbon dioxide helps in the reaction. As it is a metal, it will start corroding$.$

After some days, we will observe greenish layer on the surface of copper vessel due to the formation of copper carbonate. The required reaction is:

Copper when reacts with carbon dioxide, water and oxygen forms basic copper carbonate.

${ \boxed{ \rm{2Cu + CO_2 + O_2 + H_2O \longrightarrow CuCO_3.Cu_(OH)_2}}}$

The basic carbonate is a green coloured substance formed due time. Another example is the statue of liberty in New York, USA.