Study the given table and answer any four questions from (a) to (e): A student took the samples of four metals A, B, C and D and added the following solutions one by one. The results obtained have been tabulated as follows:
| Metal | Iron (II) Sulphate | Copper (II) Sulphate | Zinc Sulphate | Silver Nitrate |
| A | No reaction | Displacement | - | - |
| B | Displacement | - | No reaction | - |
| C | No reaction | No reaction | No reaction | Displacement |
| D | No reaction | No reaction | No reaction | No reaction |
(a) Choose the most reactive metal:
(i) A
(ii) B
(iii) C
(iv) D
Answer
- According to the reactivity series , among the 4 salts given, Zinc Sulphate is the most reactive .
- Since no metals react with it, we consider the next most reactive solution, Iron (II) Sulphate .
- Since only B is able to displace Iron from Iron (II) Sulphate, it is the most reactive among A,B,C,D
So, the correct answer is (i) B
(b) Which of the following will displace Cu from its solution of sulphate:
(i) A only
(ii) B only
(iii) Both A and B
(iv) None of the above
Answer
From the given table, it is seen that
- A is able to displace Cu from Copper (II) Sulphate.
- Since B is more reactive than A , it will also be able to displace Cu.
So, the correct answer is (iii) Both A and B
(c) Which is the correct decreasing order of reactivity?
(i) B > A > C > D
(ii) A > B > D > C
(iii) D > B > A > C
(iv) B > A > D > C
Answer
Let us go in order of most reactive to least reactive salt solutions.
- Zinc solution is the most reactive salt solution here. But no metal reacts with it .
- B is the most reactive element as it is able to displace Iron from its salt solution .
- A is able to displace copper from its salt solution.
- C is able to displace Silver from its salt solution.
- D is the least reactive element, since it does not react at all .
So, the correct option is (i) B > A > C > D
(d) The gas produced when dil. HCl is added to a reactive metal:
(i) Oxygen
(ii) nitrogen
(iii) hydrogen
(iv) none of the above
Answer
The reaction of a reactive metal with dil HCl is as follows:
2M + 2dil HCl→ 2MCl+ H 2 ↑
Where M is any reactive metal.
So, the correct option is (iv) Hydrogen
(e) On the basis of sequence of reactions, identify the most and least reactive elements.
A + BX → AX + B
C + AY → CY + A
(i) Most reactive: C; Least reactive: B
(ii) Most reactive: B; Least reactive: C
(iii) Most reactive: A; Least reactive: B
(iv) Most reactive: B; Least reactive: A
Answer
- A is able to displace B from its salt solution BX. So, A is more reactive than B
- C is able to displace A from its salt solution AY. So, C is more reactive than A and therefore, also more reactive than B
Hence, C is most reactive and B is least reactive
So, the correct option is (i) Most reactive: C; Least reactive: B
