1 is c 2 is b 3 is 1 d 4 is a
Answer:
Neither
Explanation:
Even though the average between the 4 measurements is 7.45, the measurements are not accurate. This is probably due to the pH meter being out of calibration or because there is some contamination in the buffer solution
I need a little more context but I believe you are correct
1.regulating ph
2.heating
3.adding some oppositely charged colloids