Answer: D
Explanation:
Because velocity is speed
Since protons are postive and neutrons are neutral. Then it is postive.
the mass number of fluorine (F) is 19
C. 19
It is letter C: Continental crust is thicker than oceanic crust.
The balanced equation would be 
<h3>Electrochemical equations</h3>
Zn reacts with Cu solution according to the following equation:

In the reaction,
is reduced according to the following: 
While Zn is oxidized according to the following: 
Thus, giving the overall equation of; 
More oxidation-reduction equations can be found here: brainly.com/question/13699873
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