The blue colour of crystals of a substance changed on heating in a closed test tube but the colour was regained after some time on cooling. Name the substance and write its chemical formula. Explain the phenomenon involved.

When in the blue solution of copper sulphate, Zinc srtip is dipped, after some time colour changes to:

Crystals copper sulphate are heated in a test tube for some time. What is the colour of copper sulphate crystals (i) before heating and (ii) after heating.

The crystals of compound A on keeping in air get converted into a white powder. Its solution in water gives blue colour with red litmus. It is used to remove permanent hardness of water. Identify the substance. Write chemical formula of its crystalline form.

A student performed the experiment of heating ferrous sulphate crystals in a boiling tube. He smell fumes of a pungent gas saw colours of ferrous sulphate disappear Write the chemical formula of the pungent gas

The crystals of compound A on keeping in air get converted into a white powder. Its solution in water gives blue colour with red litmus. It is used to remove permanent hardness of water. Write two main uses of the substance.

On heating blue coloured powder of copper nitrate in a boiling tube, copper oxide(black) oxygen gas and a brown gas X is formed Write a balanced chemical equation of the reaction.

Concentrated sulphuric acid is added followed by heating to each of the following test tubes labelled (i) to (v). Identify in which of the above test tube the following change will be observed. Support your answer with the help of a chemical equation. Formation of black substance.

Concentrated sulphuric acid is added followed by heating to each of the following test tubes labelled (i) to (v). Identify in which of the above test tube the following change will be observed. Support your answer with the help of a chemical equation. Formation of black substance.

A substance 'S' is used as a building material and is insoluble in water. When reacted with dil H_2SO_4 it produces a gas 'X' which turned lime water milky. When the liberated gas 'K' passed in excess, the milkiness disappeared. Write the name and chemical formula of S and its reactions will dil H2SO4, name the acid and base from which the substance 'S' is made.