If a loop contains voltage drops of $2\text{ V}$, $3\text{ V}$, and $5\text{ V}$, what source voltage $V_s$ satisfies Kirchhoff's Voltage Law?

Kirchhoff's Voltage Law requires total rise to equal total drop in a single closed loop. The total drop is $2+3+5=10\text{ V}$, so the source must be $V_s=10\text{ V}$.