The correct answer is option 1, which states that both statement 1 and statement 2 are correct.
Statement 1 is correct because temporary hardness of water is indeed caused by the presence of soluble magnesium and calcium hydrogen carbonate. Temporary hardness occurs when these compounds dissolve in water, resulting in the formation of calcium and magnesium ions.
Statement 2 is also correct because boiling can remove temporary hardness. When water is boiled, the soluble magnesium and calcium hydrogen carbonate decompose, forming insoluble calcium carbonate and magnesium hydroxide. These precipitates can then be removed through filtration or settling.
Statements 3 and 4 are incorrect. Calgon`s method, mentioned in statement 3, is not used to remove temporary hardness, but rather to prevent the adverse effects of hard water by binding to calcium and magnesium ions. Clark`s method, mentioned in statement 4, is not used to remove permanent hardness, but rather to determine the permanent hardness of water through a titration method.
It is important to note that permanent hardness of water can only be removed through ion exchange or chemical processes. Therefore, statement 4 is incorrect as well.
In conclusion, option 1 is the correct answer, as both statement 1 and statement 2 correctly describe the property of hard water.