Which half reaction equation correctly represents a reduction reaction?

a. Li + e- --> Li+

b. Na + e- --> Na+

c. Br2 + 2e- --> 2Br-

d. Cl2 + e- --> 2Cl-

The half-reaction equations that correctly represent a reduction reaction are

c. Br₂ + 2e- --> 2Br-

d. Cl₂ + e- --> 2Cl-

Explanation:

The reduction corresponds to the electron gain of an atom, ion or molecule, that is, it is a reaction in which a substance captures electrons. In other words, there is reduction whenever an atom or group of atoms gains electrons, increasing its negative charges or decreasing the positive ones.   In this way, the oxidation state decreases.

The half-reaction equations that correctly represent a reduction reaction are

c. Br₂ + 2e- --> 2Br-

d. Cl₂ + e- --> 2Cl-

the ratio of the conjugate base to the acid required to attain the desired ph.

a electronegativity decreases beacuse the size of nucleus is bigger.