Which solution has the greatest number of hydroxide ions?
baking soda, ph = 9
milk, ph = 6
tomato juice, ph = 3.5
vinegar, ph = 2

Option A: baking soda, pH=9

The number of hydroxide ions or concentration of hydroxide ions depends on pOH of solution as follows:

This means more the value of pOH, smaller will be the number of hydroxide ions.

Thus, solution with smaller value of pOH, will have greatest number of hydroxide ions.

Also, pH and pOH are related to each other as follows:

Calculating pOH from all the given pH values,

pOH of baking soda:

pOH=14-9=5

pOH of milk:

pOH=14-6=8

pOH of tomato juice:

pOH=14-3.5=10.5

pOH of vinegar:

pOH=14-2=12

here, baking soda has smallest pOH value, thus, it will have greatest number of hydroxide ions.

Also, more the basic is solution, more it will have hydroxide ions, or more is the value of pH more the solution is basic. The pH of baking soda is maximum that is 9 thus, it is most basic among given options and contain greater number of hydroxide ions.

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).