Answer
(a) So final charge on each object is $-1.6μC$
(b)$10^{13}$ electrons are responsible for final charge on each electron.
Work Step by Step
Charges on identical metallic objects are
$q_{1}=+1.6\mu C$
$q_{2}=+6.2\mu C$
$q_{3}=-4.8\mu C$
$q_{4}=-9.4\mu C$
(a) When objects are brought simultaneously into contact, then there will be a net charge $q=q_{1}+q_{2}+q_{3}+q_{4}$
$q=1.6\mu C+6.2\mu C+(-4.8\mu C)+(-9.4\mu C)$
Net charge $q=−6.4μC$
this charge will equally distribute among all so charge on each metallic object will be
$q_{1}=q_{2}=q_{3}=q_{4}=\frac{q}{4}=\frac{−6.4μC}{4}=-1.6μC$
So final charge on each object is $-1.6μC$
(b) charge is negative so electrons make up the final charge
$-1.6μC =-1.6\times10^{-6}C$
$-1.6\times10^{-19}C$ is equal to $1$ electron
$-1C$ is equal to $\frac{1}{1.6\times10^{-19}} $electron
$-1.6\times10^{-6}C$ is equal to $\frac{1.6\times10^{-6}}{1.6\times10^{-19}} $electron = $1\times10^{13}$ electrons
$10^{13}$ electrons are responsible for final charge on each electron.
