When an aqueous solution of ammonia is added to an aqueous solution of cupric sulfate,which substance forms a pale blue precipitate?

How will you test whether the gas evolved in a reaction is hydrogen?

Who discovered the electron?

Give reasons for the following:
$(i)$ Moist air and acidic gases are not good for some metals.
$(ii)$ Chips manufacturers usually flush bags of chips with nitrogen gas.

Write the balanced chemical equations for the following reactions:
$(a)$ Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogencarbonate.
$(b)$ Sodium hydrogencarbonate on reaction with hydrochloric acid gives sodium chloride,water,and liberates carbon dioxide.
$(c)$ Copper sulphate on treatment with potassium iodide precipitates cuprous iodide $(Cu_2I_2)$,liberates iodine gas,and also forms potassium sulphate.

Write a balanced chemical equation with state symbols for the following reactions.
$(i)$ Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
$(ii)$ Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.