Q52 of 152 Page 22

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?

(a) Metal, M is Sodium (Na).

(b) Solution S is Sodium hydroxide solution (NaOH solution). It is Alkaline.


(c) Gas G is Hydrogen (H2).


(d) 2Na + 2H2O → 2NaOH + H2


(e) The reaction is Exothermic.



More from this chapter

All 152 →
50 A silvery-white metal X taken in the form of ribbon, when ignited, burns in air with a dazzling white flame to form a white powder Y. When water is added to powder Y, it dissolves partially to form another substances.

(a) What could metal X be?


(b) What is powder Y?


(c) With which substance metal X combines to form powder Y?


(d) What is substance Z? Name one domestic use of substance Z.


(e) Write a balanced chemical equation of the reaction which takes place when metal X burns in air to form powder Y.

 51 A metal X forms a salt XS04. The salt XS04 forms a clear solution in water which reacts with sodium hydroxide solution to form a blue precipitate Y. Metal X is used in making electric wires and alloys like brass.

(a) What do you think metal X could be?


(b) Write the name, formula and colour of salt X S04


(c) What is the blue precipitate Y?


(d) Write a chemical equation of the reaction which takes place when salt XS04 reacts with sodium hydroxide solution. Give the state symbols of all the reactants and products which occur in the above equation.

 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.

 54 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?