Chemistry
Aman performed the following four experiments

The experiments in which the blue colour of the solution will fade are :
P and Q
P, Q and R
Q and R
Q, R and S
Chemical Reaction
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Answer
Q and R
Reason — Blue colour is because of CuSO4. In experiment Q, zinc displaces copper from copper sulphate solution because zinc is more reactive and present above copper in reactivity series.
CuSO4 (aq) + Zn ⟶ ZnSO4 + Cu ↓
In experiment R, iron displaces copper from copper sulphate solution because iron is also more reactive and present above copper in reactivity series.
Hence, in experiment Q and R, copper is displaced by more reactive metal. So, the blue colour of the solution will fade.
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Related Questions
FeS + H2SO4 ⟶ FeSO4 + H2S is an example of:
- Displacement reaction
- Double decomposition reaction
- Decomposition reaction
- Combination reaction
Which of the following statements is/are correct with respect to the figure shown alongside?

P — A is HCl, B is iron.
Q — A is Cl2, B is copper.
R — A is Cl2, B is iron.
Only P
Only Q
Only R
Both P and R
The figure given below demonstrates the preparation of oxygen.
2KClO3 (s) 2KCl (s) + 3O2 (g)

(I) Which of the following statements is/are correct about the reaction?
It is a decomposition reaction and is exothermic.
It is a decomposition reaction and is endothermic.
It is a photochemical decomposition reaction.
It is a combination reaction.
(II) Potassium chlorate is:
an oxidising agent.
a reducing agent.
both reducing as well as an oxidising agent.
all options are correct.
(III) In the reaction, manganese dioxide:
takes part in the reaction.
acts as a catalyst.
decreases the speed of reaction.
helps in producing more oxygen.
What happens when a solution of an acid is mixed with a solution of a base in a test tube?
P — The temperature of the solution increases.
Q — The temperature of the solution decreases.
R — The temperature of the solution remains the same.
S — Salt formation takes place.
Only P
P and R
Q and R
P and S