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.

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.

Salt ‘A’ commonly used in bakery products on heating gets converted into another salt ‘B’ which itself is used for removal of hardness of water and a gas ‘C’ is evolved. The gas ‘C’ when passed through lime water, turns it milky. Identify A, B and C.

A solution of substance 'X' is used for white washing. Write the reaction of the substance X named in above with water.

A metal carbonate X on reacting with an acid gives a gas which when passed through a solution gives the carbonate black. On the other hand, A gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives compound Z, used for disinfecting water. Identify X, Y, G and Z.

In an experiment to estimate the size of a molecule of oleic acid 1mL of oleic acid is dissolved in 19 mL of alcohol. Then 1 mL of this solution is diluted to 20 mL by adding alcohol. Now 1 drop of this diluted solution is placed on water in a shallow trough. The solution spreads over the surface of water forming one molecule thick layer. Now, lycopodium powder is sprinkled evenly over the film and its diameter is measured. Knowing the volume of the drop and area of the film we can calculate the thickness of the film which will give us the size of oleic acid molecule. Read the passage carefully and answer the following questions : How will you calculate the volume of n drops of this solution of oleic acid ?

In an experiment to estimate the size of a molecule of oleic acid 1mL of oleic acid is dissolved in 19 mL of alcohol. Then 1 mL of this solution is diluted to 20 mL by adding alcohol. Now 1 drop of this diluted solution is placed on water in a shallow trough. The solution spreads over the surface of water forming one molecule thick layer. Now, lycopodium powder is sprinkled evenly over the film and its diameter is measured. Knowing the volume of the drop and area of the film we can calculate the thickness of the film which will give us the size of oleic acid molecule. Read the passage carefully and answer the following questions : What would be the volume of oleic acid in each mL of solution prepared?