A) 144 C
The electric current is defined as
![I=(q)/(t)](https://img.qammunity.org/2020/formulas/physics/middle-school/uwz13umodzqjd05pqoco8p9v1j5i5rahn3.png)
where
q is the charge passing a given point of the circuit in a given time
t is the time interval considered
For this bulb, we know that:
I = 0.20 A is the current
is the time considered
Therefore, the amount of charge passing the point in the circuit in this time is
![q=It = (0.20)(720)=144 C](https://img.qammunity.org/2020/formulas/physics/middle-school/3s5e0uz1zopseihbcmhq9bkeuphx4rycka.png)
B)
electrons
The charge of one electron is
![e=1.6\cdot 10^(-19)C](https://img.qammunity.org/2020/formulas/physics/high-school/98ae3qhks63zozpyndu35mauu82gajjadg.png)
And the total charge passing through the point in the circuit in 12 min is
![q=144 C](https://img.qammunity.org/2020/formulas/physics/middle-school/6kmffz40tpka1k6is4q9776gzvwf88tj37.png)
So the total charge can be written as
![q=ne](https://img.qammunity.org/2020/formulas/physics/college/lmzb7yqomiyngysrq3l7hofgngcc07u64u.png)
where
n is the number of electrons passing that point of the circuit in 12 min
So, solving for n,
![n=(q)/(e)=(144)/(1.6\cdot 10^(-19))=9\cdot 10^(20)](https://img.qammunity.org/2020/formulas/physics/middle-school/7u6j5imw51wx97jypcnyo4yr02nx3fnc60.png)