Q60 of 152 Page 49

When hydrogen burns in oxygen, water is formed and when water is electrolysed, then hydrogen and oxygen are produced. What type of reaction takes place:

(a) in the first case?


(b) in the second case?

(a) In the first case it is a combination reaction.

(b) In the second case it is a Decomposition reaction.



More from this chapter

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58 When a green iron salt is heated strongly, its colour finally changes to brown and odor of burning sulphur is given out.

(a) Name the iron salt.


(b) Name the type of reaction that takes place during the heating of iron salt.


(c) Write a chemical equation for reaction involved.

 59 A colourless lead salt, when heated, produces a yellow residue and brown fumes.

(a) Name the lead salt.


(b) Name the brown fumes.


(c) Write a chemical equation of the reaction involved.

 61 A strip of metal X is dipped in a blue coloured salt solution YSO4. After some time, a layer of metal Y form the salt solution is formed on the surface of metal strip X. Metal X is used in galvanization whereas metal Y is used in making electric wires. Metal X and metal Y together form an alloy Z.

(a) What could metal X be?


(b) What could metal Y be?


(c) Name the metal salt YSO4.


(d) What type of chemical reaction takes place when metal X reacts with salt solution YSO4? Write the equation of the chemical reaction involved.


(e) Name the alloy Z.

 62 When a black metal compound XO is heated with a colourless gas Y2, then metal X and another compound Y2O are formed. Metal X is red-brown in colour which does not react with dilute acids at all. Gas Y2 can be prepared by the action of a dilute acid on any active metal. The compound Y2O is a liquid at room temperature which can turn anhydrous copper sulphate blue.

(a) What do you think is metal X?


(b) What could be gas Y2?


(c) What is compound XO?


(d) What is compound Y2O?


(e) Write the chemical equation of the reaction which takes place on heating XO with Y2.


(f) What type of chemical equation of the reaction which takes place on heating XO with Y2.