Question

A student made the observations after studying the following displacement reactions between

a metal and a salt solution of different metal:

(i) Mg + ZnSO4 -> MgSO4 + Zn

(ii) Zn + CuSO4-> ZnSO4 + Cu

(iii) Ca + MgSO4-> CaSO4 + Mg

Select the incorrect observation(s):

(I) Calcium will displace copper from copper sulphate solution.

(II) Magnesium will be displaced by both calcium and zinc

(III) The least reactive metal out of Mg, Ca, Cu and Zn is Zinc.

(IV) The most reactive metal out of Mg, Ca, Cu and Zn is calcium.

(a) Both (I) and (II)

(b) Both (I) and (III)

(c) Both (II) and (III)

(d) Both (I) and (IV)​

Answer 1

Answer:

c

Ca most reactive then Mg , Zn ,Cu

Answer 2

Final Answer: Option C is the correct option.

Explanation: By Using the electrochemical series

    (I) By adding the zinc calcium displaces the copper from copper sulphate solution because in the electrochemical series zinc is above the copper.

So, this is a correct statement.

(II)  Calcium and zinc both cannot displace magnesium because both elements lie below the magnesium in the electrochemical series.

So, this is a wrong statement.

(III) In the electrochemical series, Cu lies below the Zn, Ca, and Mg. Cu is most reactive.

So, this is also a wrong statement.

(IV) The most reactive metal out of Mg, Ca, Cu, and Zn is calcium because Ca is lies above in the electrochemical series.

So, this is the right statement.

Hence, option (c) is the correct option.