Question

6. In the neighborhood of your school, hard water required for an experiment is not available. Select from the following groups of salts available in your school, a group each member of which, if dissolved in distilled water, will make it hard:

• A. Sodium chloride, calcium chloride
• B. Potassium chloride, sodium chloride
• C. Sodium chloride, magnesium chloride
• D. Calcium chloride, magnesium chloride

Answer 1

The correct option is D

Calcium chloride, magnesium chloride

In hard water ${\mathrm{Ca}}^{2+}$ and ${\mathrm{Mg}}^{2+}$ ions are present. Calcium chloride and magnesium chloride contains ${\mathrm{Ca}}^{2+}$and ${\mathrm{Mg}}^{2+}$ ions. So, ${\mathrm{CaCl}}_2$ and ${\mathrm{MgCl}}_2$ dissolved in distilled water make the water hard.

Final answer:

Hence, option (D) is the correct option.