It is the same as a proton. That is why, if hydrogen was a molecule not an ion, one electron is needed to 'cancel' out the proton.
Again great job! They all look correct except 20. is 3.7 due to sig fig of least precision, which you have a mark by!! You don't even need help!;) Here comes the next chemical engineer! :)
ANSWER:
the answer is burning as it is a chemical change emaning that the substance changes chemically, the other choices are exp of physical changing meaning they stay the same substance but change physically
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