For basic solutions, which element is added to balance half-reactions? chlorine hydroxide iron nitrogen

Hydroxide ion

Explanation: The question is to balance half -reactions in basic solutions(medium) and not to neutralize the basic solutions.

In acidic medium, half-reactions are balanced by adding and where as the half-reactions in basic medium are balanced by adding and .

As the question asks about balancing  half-reactions in basic solutions, the right choice is hydroxide ion.

Chlorine, Iron or nitrogen are not used for balancing half reactions.

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation: