Name or state the following.

1. An efflorescent decahydrate salt.
2. A deliquescent salt of a trivalent metal.
3. A liquid hygroscopic substance.
4. A salt whose solubility decreases with rise in temperature of the solvent water.
5. A substance added to remove both temporary and permanent hardness in water.

1. Washing soda (Na₂CO₃.10H₂O)
2. Iron (III) chloride (FeCl₃)
3. Concentrated sulphuric acid (conc. H₂SO₄)
4. CaSO₄
5. Washing soda (Na₂CO₃)