The rate of a chemical reaction can be measured by monitoring the change in concentration of a reactant per unit time.
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true

Explanation:

Concentration is the number of moles of an element per volume.

As a chemical reaction proceeds, moles of the reactannts are used per unit time, hence, change in concentration per unit can be used to measure the rate of chemical reaction.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.