Litmus is an indicator
Charged particles are ions
Acids contain H+ ions
Bases contain OH - ions
Hydronium ions are H3O+
Now, I have to take issue with the last one
A base of pH 14 is not a strong base, it would be a highly concentrated base. A strong base is a base that completely deionizes in water.
But technically, for the purpose of your answer strong base = pH 14
B. 8
Although it may seem that transition metals would have more than 8 valence electrons, they in fact do not.
I found this is the order of activity in Internet
Mn>Zn>Cr>Fe>Cd>Co>Ni>Pb
You can see that Fe is between Cr and Cd
Cr is more active than Fe and Fe is more active than Cd.
The Fe will displace Cd but not Cr.
Answer:Fe
