question_answer

  A tarnished copper vessel begins to shine again when rubbed with lemon. Why?

Answer:

                  The acids which ionise almost completely are called strong acids, e.g., mineral acids .                                         (1) The acids which ionise only partially or to a lesser extent are called weak acids, e.g., organic acids.                                                                (1) (i) Strong acids Hydrochloric acid, nitric acid, sulphuric acid.                                                (1/2) (ii) Weak acids Citric acid, acetic acid, formic acid.                                                                  (1/2)