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SCIENCE & TECHNOLOGY (Class-10) Acids, Base and Salts

1. What is the chemical name of washing soda? (1mark)
2. When sodium hydrogen carbonate is added to water, the hydrogen ion concentration decreases.What is the nature of the solution? Acidic or basic? (1mark)
3. Write the chemical name and formula of bleaching powder. (1mark)
4. A milkman adds a very small amount of baking soda to fresh milk. (2 marks) (a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
5. Plaster of Paris should be stored in a moisture proof container. Explain why? (2 marks)
6. What is a neutralization reaction? Give two examples. (2 marks)
7. Explain how pH change in the river water can endanger the lives of aquatic animals like fish.
8. What happens when (2 marks) (i) plaster of Paris is heated to 473 K? (ii) plaster of Paris is mixed with water?
9. Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example.
How will you test for the presence of this gas? (3 marks)
10. Explain the pH change as the cause of tooth decay. How can tooth decay caused by pH change be prevented? (3 marks)
11. Name the raw material used for the preparation of plaster of Paris. Write an equation to show the reaction between Plaster of Paris and water. What will happen if heating is not controlled while preparing plaster of Paris? (3 marks)
12. (i) Why are acids not stored in meal containers? Containers made from which material are safe to store acids.
(ii) Explain why does dry hydrochloric acid not conduct electricity but its aqueous solution conducts electricity.
(iii) Why are commercial samples of bleaching powder not completely soluble in water?
Or
Write one activity to show the reaction of acids with metal carbonates/bicarbonates salts.
(5 marks)

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