Chemistry
Assertion (A): Hardness of water is removed by boiling.
Reason (R): Water contains dissolved calcium and magnesium chlorides.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
A is false but R is true.
Explanation — Hardness of temporary hard water which contains only hydrogen carbonates of calcium and magnesium can be removed just by boiling. Water containing sulphates and chlorides, of magnesium and calcium is called permanent hard water. This hardness cannot be removed by boiling. Hence the assertion (A) is false.
Water of some springs, wells and rivers contain dissolved mineral matter like hydrogen carbonates, sulphates or chlorides of calcium and magnesium, turning the water hard. Hence the reason (R) is true.
Related Questions
Assertion (A): Phosphorus when dissolved in carbon disulphide is a non aqueous solution.
Reason (R): Solutions of substances in a solvent other than water are called non aqueous solutions.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Concentrated sulphuric acid absorbs moisture from the atmosphere.
Reason (R): Conc. H2SO4 is a deliquescent substance.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Name:
(a) The solute and solvent in sugar solution.
(b) The characteristic property which makes water the universal solvent.
(c) A substance whose solubility shows an anomalous behaviour.
(d) A substance whose solubility rapidly increases with the temperature.
What is the composition of water ? In what volume its elements combine ?