Answer:
b i. The curve would be less steep than both of the graphs.
c. The temperature was the same at the start of the experiment so that the only variable changed in the experiment would be the thickness of the walls and the change in temperature can be measured from the same starting temperature, ensuring a fair experiment.
Step-by-step explanation:
b i. Since you know that a thicker wall conducts heat from the inside room to the surroundings slower (based on my previous answer ;)), heat from the room would be conducted to the surroundings by the thicker wall slower and the temperature change will be less drastic and the graph would be less steep.
c. In an experiment, only one independent variable can be changed and we would normally record the dependent variable to get a conclusion for the experiment as the dependent variable is the variable that is affected by the independent variable. We should not change any other variable in the experiment, such as the starting temperature of the experiment.
For e.g. If you want to find out how the amount of water affects a plant's growth, the amount of water would be the independent variable and that would be the only thing you would change in that experiment. During the experiment, you would record the dependent variable, which is the height of the plant. The type of plants used and the type of soil..etc should be kept the same/constant so that it is a fair experiment, as a better type of soil may make the plant grow taller.