Question

1. which of the elements in the following reaction has been reduced?

zn + 2h⁺ → zn²⁺ + h₂
options:
both hydrogen and zinc
zinc
neither hydrogen nor zinc
hydrogen

Explanation:

Step1: Find Zn oxidation state

Elemental Zn: oxidation state = $0$; $\text{Zn}^{2+}$: oxidation state = $+2$

Step2: Find H oxidation state

$\text{H}^+$: oxidation state = $+1$; $\text{H}_2$: oxidation state = $0$

Step3: Identify reduction

Reduction = oxidation state decrease. H goes from $+1$ to $0$.

Answer:

Hydrogen