Class 11th| Chemistry Viva-Voce Questions answers

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Q1. What do you mean by a saturated solution?

Ans. No more solute is dissolved at room temperature in a solution is known as a saturated solution.

Q2. How does potash alum help in the purification of water?

Ans. Dust parricles being negatively charged are coagulated by Al³+ions .Due to this , the dust particles settle down leaving the water clear.

Q3. What happens when potash alum is heated?

Ans. Potash alum melts at 92°C and 200°C loses all its water of crystallisation and turns to a porous mass .Anhydrous alum is known as burnt alum

Q4. Why is water of Crystallisation?

Ans. Water of crystallisation is the number of water molecules present in one formula unit of the crystalline substance.

Q5. What are the uses of potash alum?

Ans. It is used in tanning ,as a mordent for coagulating muddy water, in calico printing and for sizing paper.

Q6. What is potash alum?

Ans.Potash alum is a double salt having formula K²SO⁴.Al²(SO⁴)³.24H²O.

Q7. What will be the shape of potash alum?

Ans. Octahedral shape.

Q8. Why is the solution not concentrated too much or evaporated to dryness in the preparation of crystals ?

Ans. Otherwise we will get poor quality of crystals .

Q9. Why are potash alum crystals washed with cold water?

Ans. Potash alum is only sparingly soluble in cold water while the impurities are more easily soluble.

Q10. Will the aqueous solution of potash alum be acidic, basic or neutral?

Ans. Acidic.

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