Chemistry
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.
Answer
A is true but R is false.
Explanation — Concentrated sulphuric acid absorbs moisture (water vapour) from the atmosphere when it is exposed to air but it will not form solution. Such substances are called hygroscopic substances. Hence the assertion (A) is true.
Conc. H2SO4 is hygroscopic substances not deliquescent substance because deliquescent substance absorbs moisture from the air until it dissolves completely in the absorbed water, forming a solution. Hence the reason (R) is false.
Related Questions
Assertion (A): As the temperature is raised, the amount of solute that can be dissolved in a given quantity of solvent also increases.
Reason (R): A solution which is saturated at a given temperature, becomes unsaturated at a higher temperature.
- 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): 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): 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.
Imaad took a few blue crystals of copper sulphate. On heating the crystals, he observed that the blue colour disappeared and the substance turned into a white powder. He learnt that this change occurred due to the loss of water of crystallisation on heating. He also learnt that plaster of Paris is prepared by heating gypsum (calcium sulphate dihydrate) at 100°C.
Answer the following questions:
(a) How many water molecules are present in one formula unit of hydrated copper sulphate?
(b) Name the white powder formed after heating copper sulphate crystals.
(c) How can Imaad obtain the blue colour again from the white powder? Write the chemical equation for the reaction.
(d) Write the chemical formula of gypsum. Name the product formed when gypsum is heated at 100°C.