Q7 of 28 Page 187

Observe the given chemical change and answer the following:


i) Identify ‘A’ and ‘B’.


ii) Write the commercial name of calcium hydroxide.


iii) Identify products ‘C’ and 'D' , when HCl is allowed to react with calcium oxide.


iv) Say whether calcium oxide is acidic or basic.

(i) A is Calcium carbonate (CaCO3 ) and B is carbon dioxide (CO2). Both of these are obtained from the following reaction : -

CaO CaCO3


(ii) The commercial name of calcium hydroxide is slaked lime.


(iii) The products ‘C’ and 'D' , when HCl is allowed to react with calcium oxide are Calcium chloride(CaCl2) and water(H2O).


(iv) Calcium oxide is basic, it could be understood by its reaction with an acid as in the above case with hydrochloric acid. With hydrochloric acid it reacts to form a salt(Calcium chloride(CaCl2)) and water in the same way as a base reacts with an acid to form salt and water. Hence calcium oxide is basic


More from this chapter

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5

Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid is added to test tube A, while acetic acid is added to test tube B. The amount and concentration taken for both the acids are same. In which test tube does the reaction occur more vigourously and why?

 6

Two acids ‘A’ and ‘B’ were kept in beakers. Acid ‘A’ undergoes partial dissociation in water, whereas acid ‘B’ undergoes complete dissociation in water.

i) Of the two acids ‘A’ and ‘B’ , which is weak acid and which is strong acid?


ii) What is a weak acid?


iii) What is a strong acid?


iv) Give one example each.

 8

Take copper nitrate in a test tube and heat it over the flame.

i) What is the colour of cupric nitrate?


ii) What do you observe?


iii) Name the type of reaction that takes place.


iv) Write the balanced equation.

 9

Identify the wrong statements and correct them.

i) Sodium benzoate is used in food preservative.


ii) Nitric acid is not used as fertilizer in agriculture.


iii) Sulphuric acid is called the king of chemicals.


iv) The PH of acid is greater than 7.


v) Acetic acid is used in aerated drinks.