Random and Systematic errors (physics)

Hello guys,
so for my coursework I had to carry out an experiment and for one of the tasks it says that I have to name some random and systematic errors. I had to carry out an investigation into a range of fuel (Paraffin and ethanol) and how much energy each produces. I would appreciate if anyone can help me name some errors. Thanks!!

If you measured the mass of anything using a balance, a zero error on the balance is an example of a systematic error.

THANK YOU SO MUCH! Ihave been waiting so long for someone to answer. I appreaciate your help thank you.

No problem. Random errors are a little bit more subtle and caused by fluctuations in the experiment such as room temperature, human observation e.t.c. they can be eliminated by doing repeats and taking a mean

You're a god. life saver. lol. But thanks i appreciate your help so much. Was not a good idea to leave 2 weeks worth of work to the last minute.