Explain the following: Aqueous solution of sodium chloride is a good conductor of electricity while solid sodium chloride is a non-conductor.

Give the general trends in the properties of alkali metals. Write the principle of manufacture of potassium chlorate.

Give the comparative account of properties of alkali metals. Write any two uses of potassium chlorate.

Name the elements of group $\mathrm{l}$ of the periodic table. Give the general trends in the properties of these elements. How is Glauber's salt prepared?