Question

Assertion:  Zinc displaces copper from copper sulphate solution.

Reason: The  $ {E^0} $  of Zn is -0.76 volt and that of copper is +0.34 volt.

A) Both assertion and reason are correct and reason is the correct explanation for assertion

B) Both assertion and reason are correct but reason is not the correct explanation for assertion. 

C) Assertion is correct but reason is incorrect.

D) Assertion is incorrect but the reason is correct.

Answer 1

Hint: For solving these types of questions, we required the concept of displacement reaction and the reactivity series of the element. A displacement reaction is one in which an atom or a set of atoms is displaced by another group of atoms in a molecule. The reactivity series of the element is one in which the reactivity of the metal is given from the least reactive metal to the highest reactive metal.

Complete answer:

Using the reactivity series of the metal the products of the displacement reactions are given.

Let’s see the assertion which states that zinc displaces the copper sulphate from the solution.

As we know that a metal having smaller reduction potential can displace a metal having higher reduction potential from the solution of their salt.

Now in the reactivity series the zinc metal lies above the copper, therefore the zinc is more reactive and has lower reduction potential as compared to copper.

Therefore the zinc can displace copper from its salt solution.

 $ Zn\left( s \right) + C{u^{2 + }}\left( {aq} \right)\xrightarrow{{}}Z{n^{2 + }}\left( {aq} \right) + Cu\left( s \right) $ 

The reason given above is the value of the reduction potential of the zinc and copper which is the correct explanation of the assertion.

Both the assertion and reason are correct.

Hence, the correct option is A.

Note: In order to solve questions related to assertion and reason you have to read the statements carefully. Some of the elements of the reactivity series are potassium, sodium, barium, zinc, iron, lead, copper, silver, gold, platinum. Also remember that only a metal higher in the reactivity series replaces the other element.