Question

choose the correct answer
how long will heat continue to flow from warm to cool?
until the weight of both substances is the same
until the temperature of both substances is equal (\equilibrium\)

Explanation:

Heat transfer occurs from a warmer to a cooler body until thermal equilibrium is reached, which means the temperatures of the two substances become equal. Weight has no relation to the heat - flow process.

Answer:

until the temperature of both substances is equal ("equilibrium")