Question

Assertion: $Cu$ cannot liberate hydrogen from acids.

Reason: Because it has positive electrode potential.

• A. Both assertion and reason are true but reason is not the correct explanation of assertion.
  
• B. Both assertion and reason are false.
  
• C. Both assertion and reason are true, and reason is the correct explanation of the assertion.
  
• D. Assertion is not true but reason is true.
  

Answer 1

The correct option is C Both assertion and reason are true, and reason is the correct explanation of the assertion.


Analysing the assertion:

It is true that $Cu$ cannot liberate hydrogen gas from mineral acids like $HCl$.

Copper is placed below hydrogen in the electrochemical series.

Analysing the reason:

Copper has a positive standard reduction potential whereas the standard reduction potential of hydrogen is zero.

Also, more the reduction potential, less is the reactivity of metal. Since the reduction potential of copper is more, it will be less reactive than hydrogen. Thus, it cannot liberate hydrogen gas from acids.


Thus, copper does not liberate hydrogen by reacting with acids.

So, the reason is correct.

Hence, assertion and reason both are correct and reason is the correct explanation of assertion.
Hence, option (A) is correct.