The following half-reaction method is used to balance oxidation-reduction equations. (1) Determine which atoms change oxidation state from reactant to product in the reaction.
(2) Identify and write half reactions (oxidation and reduction).
(3) Return to the original chemical equation to balance it.
(a) Insert the coefficients from the half reactions first.
(b) Inspect the number of each atom on each side for all elements.

Which important step is missing from this procedure?

Check other reactions similar to this one.
Name the elements that are involved in the reaction.
Make sure the reduction half reaction is identified first.
Balance the half reactions based on the number of electrons.

its (D) Balance the half reactions based on the number of electrons.

Explanation:

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).