Answer:
Electrical charge, q = 75 C
Step-by-step explanation:
It is given that,
Voltage, V = 4 V
Energy stored, E = 300 J
Energy stored in the battery is given by :
![E=q* V](https://img.qammunity.org/2020/formulas/physics/college/pe92jqd9vj6pjtrn5q95dyjdmuvdt95tod.png)
q is the electrical charge
![q=(E)/(V)](https://img.qammunity.org/2020/formulas/physics/college/tl23ztnfyp2bg2bld2f18kgypcekhhxz2h.png)
![q=(300\ J)/(4\ V)](https://img.qammunity.org/2020/formulas/physics/college/4nbitxrigkhp6n5hw78bo8lrwgqi3s7wjk.png)
q = 75 C
So, the electrical charge of 75 C must flow between the battery's terminals to completely drain the battery if it is fully charged. Hence, this is the required solution.