Q54 of 152 Page 22

The white solid compound A decomposes quite rapidly on heating in the presence of a black substance X to form a solid compound B and a gas C. When an aqueous solution of compound B is reacted with silver nitrate solution, then a white precipitate of silver chloride is obtained along with potassium nitrate solution. Gas C does not burn itself but helps burn other things.

(a) What is compound A?


(b) What is compound B?


(c) What is gas C?


(d) What do you think is the black substance X? What is its function?


(e) What is the general name of substances like X?

(a) The compound A is Potassium chlorate, KClO3.

(b) The compound B is Potassium chloride, KCl.


(c) Gas C is Oxygen, O2.


(d) The black substance is Manganese dioxide, MnO2. It is a catalyst Used in decomposition of potassium Chlorate to form Oxygen gas.


(e) General name for substances like X is catalysts.



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52 The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors.

(a) What is metal M?


(b) What is solution S? Is it acidic or alkaline?


(c) What is gas G?


(d) Write a balanced chemical equation for the reaction which takes place when metal M reacts with water.


(e) Is this reaction exothermic or endothermic?

 53 When a mixture of gases X and Y is compressed to 300 atm. pressure and then passed over a catalyst consisting of a mixture of zinc oxide and chromium oxide (heated to a temperature of 300 �C), then an organic compound Z having the molecular formula CH40 is formed. X is a highly poisonous gas which is formed in appreciable amounts when a fuel burns in a limited supply of air; Y is a gas which can be made by the action of a dilute acid on an active metal; and Z is a liquid organic compound which can react with sodium metal to produce hydrogen gas.

(a) What are X, Y and Z?


(b) Write a balanced chemical equation of the reaction which takes place when X and Y combine to form Z. Indicate the conditions under which the reaction occurs.

 55 Gas A, which is the major cause of global warming, combines with hydrogen oxide B in nature in the presence of an environmental factor C and a green material D to form a six carbon organic compound E and a gas F. The gas F is necessary for breathing.

(a) What is gas A?


(b) What is the common name of B?


(c) What do you think could be C?


(d) What is material D? Where is it found?


(e) Name the organic compound E.


(f) What is gas F? Name the natural process during which it is released?

 1 What type of reaction is represented by the digestion of food in our body?