$(a)$ Define corrosion.
$(b)$ What is corrosion of iron called?
$(c)$ How will you recognise the corrosion of silver?

Which among the following statement$(s)$ is(are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to:
$(i)$ The formation of silver by decomposition of silver chloride
$(ii)$ Sublimation of silver chloride
$(iii)$ Decomposition of chlorine gas from silver chloride
$(iv)$ Oxidation of silver chloride

Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.
$(a)$ Chlorine gas is passed in an aqueous potassium iodide solution to form potassium chloride solution and solid iodine.
$(b)$ Ethanol is burnt in air to form carbon dioxide,water and releases heat.

What happens when a piece of $(i)$ Silver metal is added to copper sulphate solution? Also,write the balanced chemical equation if the reaction occurs.

Which of the following statements about the given reaction are correct?
$3 Fe (s) + 4 H_2 O (g) \rightarrow Fe_3 O_4 (s) + 4 H_2 (g)$
$(i)$ Iron metal is getting oxidised
$(ii)$ Water is getting reduced
$(iii)$ Water is acting as reducing agent
$(iv)$ Water is acting as oxidising agent

The reaction which is used in black and white photography is: