Answer: Temperature was kept as an independent variable to observe the changes in the heart beat.
Explanation:
Independent variable can be defined as the variable which can be changed to induce change in an dependent variable which is the outcome of the experiment.
According to the given situation, the temperature in which the frogs were kept changed to observe the changes in the rate of heart functioning. So, the temperature is the independent variable which changed before the experiment began.
Answer: As the temperature of the thermometer has increased it shows that that the reaction that has taken place was exothermic. In exothermic reactions heat is given out and temperature of the surroundings increases which is indicated by the increase in temperature of the thermometer.
