Solutions of Metals and Non-metals (Page No - 137) - Chemistry Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Question 94:
In a solution of lead acetate, a strip of metal M was dipped. After some time, lead from the solution was deposited on the metal strip. Which metal is more reactive, M or lead ?
Solution :
M is more reactive than lead since it is able to displace lead from lead acetate solution

Question 95:

CuSO₄(aq) + Fe(s)  -- >  FeSO₄(aq) + Cu(s)

FeSO₄(aq) + Zn(s)  -- >   ZnSO₄(aq) + Fe(s)

On the basis of the above reactions, indicate which is most reactive and which is least reactive metal out of zinc, copper and iron.
Solution :
Zinc is most r eactive and copper is least reactive out of the three since iron displaced copper from its solution and zinc displaced iron from its solution.

Question 96:
Which of the following reactions will not occur ? Why not ?

Solution :
Reaction (a) will not occur because Cu is less reactive than Mg
Reaction (c) will also not occur because Fe is less reactive than Mg .

Question 97:
In nature, metal A is found in a free state while metal B is found in the form of its compounds. Which of these two will be nearer to the top of the activity series of metals ?
Solution :
Metal B will be nearer to the top of the activity series since it is highly reactive and is hence found in the form of its compounds and not in free state.

Question 98:
If A, B, C, D, E, F, G, H, I, J and K represent metals in the decreasing order of their reactivity, which one of them is most likely to occur in a free state in nature ?
Solution :
K being the lowest in the reactivity series is least reactive and is most likely to occur in a free state in nature.

Question 99:
(a) Name a metal for each case :
(i) It does not react with cold as well as hot water but reacts with steam.
(ii) It does not react with any physical state of water.
(b) When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so ?
Solution :
(a) (i) Iron (ii) Gold
(b) More heat is evolved during the reaction of sodium metal with water due to which the hyd rogen gas formed catches fire. O n the other hand, less heat is evolved during the reaction of calcium metal with water which cannot make the hydrogen gas bu rn .

Question 100:
A zinc plate was kept in a glass container having CuS0₄ On examining it was found that the blue colour of the solution is getting lighter and lighter. After a few days, when the zinc plate was taken out of the solution, a number of small holes were noticed in it. State the reason and give chemical equation of the reaction involved.
Solution :
Zinc metal is more reactive than copper. Some of the zinc metal of zinc plate dissolves and displaces copper from copper sulphate solution. This dissolving of zinc metal forms tiny holes in zinc plate. Blue colour of copper sulphate solution gets lighter and lighter due to the formation of colourless zinc sulphate solution.