Answer:
The time of heating
Explanation:
Let us analyse the experiment closely; the temperature of the liquid increases as the time of heating increases. This implies that the temperature of the liquid is dependent on the time of heating of the liquid. The longer the time of heating, the greater the increase in temperature until the boiling temperature is eventually attained.
Hence, the temperature of the liquid is the dependent variable, the time of heating is the independent variable when the heating rate is held constant.