A sample of common salt obtained from seawater contains $39 \mathrm{g}$ of $\mathrm{NaCl}$ and $1 \mathrm{g}$ of $\mathrm{KCl}$. If it is dissolved in $100 \mathrm{g}$ of water and then $90 \mathrm{g}$ of water is evaporated, what observation do you find at $0 °\mathrm{C}$? What is the maximum amount of pure $\mathrm{NaCl}$ that can be obtained by the above method? (solubilities of $\mathrm{NaCl}$ and $\mathrm{KCl}$ are $40 \mathrm{g}$ and $55 \mathrm{g}$ at $100 °\mathrm{C}$ and $35 \mathrm{g}$ and $28 \mathrm{g}$ at $0 °\mathrm{C}$ respectively).

Solubility curves of two salts are shown above. Two processes A and B are carried out in the following ways. In process A, saturated solution of salts I and II at taken at $30 °\mathrm{C}$ and could slowly to $10 °\mathrm{C}$. In process B hot saturated solutions of I and II are cooled from $70 °\mathrm{C}$ to $50 °\mathrm{C}$. Identify the salt precipitated in process A and give reason.

Solubility curves of two salts are shown above. Two processes A and B are carried out in the following ways. In process A, saturated solution of salts I and II at taken at $30 °\mathrm{C}$ and could slowly to $10 °\mathrm{C}$. In process B hot saturated solutions of I and II are cooled from $70 °\mathrm{C}$ to $50 °\mathrm{C}$. Are the precipitated crystals in processes A and B same? Justify your answer.

Solubility curves of two salts are shown above. Two processes A and B are carried out in the following ways. In process A, saturated solution of salts I and II at taken at $30 °\mathrm{C}$ and could slowly to $10 °\mathrm{C}$. In process B hot saturated solutions of I and II are cooled from $70 °\mathrm{C}$ to $50 °\mathrm{C}$. $750 \mathrm{g}$ of saturated solution of salt I and II is prepared at $40 °\mathrm{C}$. Calculate the mass of each salt present in the solution.

A desiccating material is used as a dehumidifying agent for absorbing moisture from highly humid air and again it is made reusable by low humid air. What is the principle involved in this process?