A sample of water is given in a trough. State how would you prove experimentally whether the given sample is hard water or soft water.

Two samples of water are placed in a beaker individually. State how you will determine experimentally which of the two samples contains permanent hard water.

Select the correct word from the words in brackets to complete each sentence :

1. If pressure on the surface of water increases it's boiling point …………… and freezing point …………… [increases/decreases].
2. A saturated solution can be converted to an unsaturated solution by …………… [increasing/decreasing] the amount of the solvent.
3. Dissolved air in water contains a …………… [higher/lower] percentage of oxygen than ordinary air.
4. At low temperatures the solubility of a gas in water is …………… [less/more] compared to that at ordinary temperatures.
5. Efflorescence occurs when the vapour pressure of the hydrated crystals is …………… [more/less] than the vapour pressure of the atmospheric humidity.

Select the correct answer from the choice given in the brackets.

1. An anhydrous crystal. [blue vitriol / epsom salt / lead chloride].
2. A substance which causes hardness in water. [NH₄Cl/CaCl₂/NaCl]
3. A deliquescent salt of a divalent metal. [CuCl/CaCl₂/FeCl₂/PbCl₂]
4. An anhydrate of a heptahydrate salt. [Cu(NO₃)₂/Ca(NO₃)₂/FeSO₄/CaSO₄]
5. A drying agent, deliquescent in nature used in a dessicator. [conc. H₂SO₄/ fused CaCl₂/FeCl₃]