Consider the chemical reaction below. Upper Z n (s) plus 2 upper H superscript plus (a q) right arrow upper Z n superscript 2 plus (a q) upper H subscript 2 (g). Which half reaction correctly represents reduction for this equation? Upper Z n (s) right arrow upper Z n superscript 2 plus (a q) plus 2 e superscript minus. 2 upper H superscript plus (a q) plus 2 e superscript minus right arrow upper H subscript 2 (g). Upper Z n (s) right arrow 2 upper Z n superscript 2 plus (a q) plus e superscript minus. 2 upper H plus (a q) plus e superscript minus right arrow upper H subscript 2 (g).

2 upper H plus (a q) plus e superscript minus right arrow upper H subscript 2 (g)

Or 2H^+(aq) + e^- => H2(g)

Explanation:

That is the answer because reduction means gain of electron.

In the selected option, hydrogen being deficient of one electron gains one electron to be librated as hydrogen gas.

Other options are wrong because zinc atom is not deficient of electrons and cannot gain more electrons at that state.

2 upper H superscript plus (a q) plus 2 e superscript minus right arrow upper H subscript 2 (g).

The above option is not the right option because hydrogen does not gain two electrons to be librated. It is a group 1 element and so can only gain 1 electron.