An iron nail dipped in copper sulphate solution turns brown. This is due to which one of the following types of reactions?

Which one of the following is not an oxidation reaction?

Copper sulphate crystals available in the market are blue coloured crystals. By careful heating, they turn to white colour. Which one of the following is responsible for the blue colour ?

Which one of the following is not an example of an oxidation reaction?

Which of the following slows down the reaction rate?

Which one among the following is an example of oxidation reaction?