Equal pieces of zinc and copper are added separately to dilute sulphuric acid. Which observation is CORRECT?

Correct Option: Only zinc evolves hydrogen gas

Step-by-Step Explanation:

1. Reactivity of Metals:
The reaction of metals with dilute acids depends on their position in the electrochemical series (reactivity series) relative to hydrogen.

2. Comparing Zinc and Copper with Hydrogen:
- Zinc (Zn): Zinc is placed above hydrogen in the reactivity series. This means zinc is more reactive than hydrogen and can easily reduce hydrogen ions (${\text{H}}^{\text{+}}$) present in the acid to form hydrogen gas (${\text{H}}_2$).
- Copper (Cu): Copper is placed below hydrogen in the reactivity series. This means copper is less reactive than hydrogen and cannot displace hydrogen from dilute acids under standard conditions.

3. Chemical Reactions:

When zinc is added to dilute sulphuric acid (${\text{H}}_2{\text{SO}}_4$), a single displacement reaction occurs with the evolution of hydrogen gas bubbles:

$\text{Zn(s)}+{\text{H}}_2{\text{SO}}_4\text{(aq)}\to {\text{ZnSO}}_4\text{(aq)}+{\text{H}}_2\text{(g)}\uparrow$

When copper is added to dilute sulphuric acid, no reaction takes place:

$\text{Cu(s)}+{\text{H}}_2{\text{SO}}_4\text{(aq)}\to \text{No Reaction}$

Therefore, only zinc evolves hydrogen gas when equal pieces of zinc and copper are added separately to dilute sulphuric acid.