what kind of errors of the procedural, systematic, and random errors could possibly occur while finding the mass of a burning candle by placing a candle on an electronic scale and lighting it?

Answer 1

A procedural error would be to light it with a blowtorch and blow some of the liquid wax off onto the floor.

If the scale is incorrectly calibrated it will give you a systematic error.

You would notice random errors if you did many trials and got a scattering of answers with not noticeable cause for the scatter. As a physicist, I believe that for a classical experiment like this, errors that appear to be random are actually proceedural - you are not doing quite the same experiment each time.