Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows. 

Use the Table above to answer the following questions about metals

A, B, C and D.

(i) Which is the most reactive metal?

(ii) What would you observe if B is added to a solution of Copper(II) sulphate?

(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Answer

(i)

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

(ii) What would you observe if B is added to a solution of Copper(II) sulphate?

B is more reactive than Fe, which in turn is more reactive than Cu.

And so, B will displace Cu from its salt solution.

(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

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 reactivity series in decreasing order is given as

B>A>C>D