2) At a temperature of 200 K, a closed cylinder contains gas at a pressure of 400kPa. If the temperature increases to 280 K, what is the new
pressure? V1 = V2 (combined gas law)

The correct answer would be b) volume versus temperature, because they are also directly proportional.

Abronsted lowry acid by donating a proton

In order to improve results, many different steps can be taken into account. 1) using more precise scales and thermometers is always something that should be considered as being precise means that you are more exact with your answer.2) increasing the sample size should also be considered, if you have a bigger sample size you are able to determine if your results are accurate as well as if there are any variables that should be taken into account plus it assists in the statistical analysis and produces overall better data3) using better handwriting is also a plus, along with organizing the data properly so that others are also able to read the results and even redo the experiment in the future if it is needed.