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Subject :NSO    Class : Class 10

Rohan took 10 mL of freshly prepared iron sulphate solution in four different test tubes and added four different metal strips to each test tube as shown below:
In test tubes I and III, black residue was obtained while in test tubes II and IV, no change was observed. Metals P, Q, R and S could be respectively

A Al, Cu, Pb, Ag
B Pb, Cu, Ag, Al
C Zn, Al, Cu, Ag
D Zn, Cu, Al, Ag

Ans 1: (Master Answer)

Class : Class 1
Here, the answer is D. Black residue is obtained in test tubes I and III i.e., iron gets displaced in test tubes I and III. Therefore, metals P and R should be more reactive than iron. No change is observed in test tubes II and IV hence, metals Q and S should be less reactive than iron.

Ans 2:

Class : Class 5
Since the residue obtained was black in colour and we know that only Zinc and Copper on reacting with Iron give a black residue hence the answer is Option D

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