Q4: Two fixed charges, 1 c and -3 C are separated by 10cm as shown in figure 2.7 (a)
where may a third charge be located so that no
force acts on it? (b) is the equilibrium stable or
unstable for the third charge?

The chemical reactions lab we did is typically called a "copper plating lab,  because the acid solution cleaned the pennies and made the copper look shinier;   the acid solution cleaned the paperclips and made them look like pennies;   &   the copper from the pennies was removed, and then added to the paperclips.