If hydrogen were used as a fuel, it could be burned according to the following reaction:
H2(g) + 1/2O2(g) > H2O(g).
A) Use average bond energies to calculate ΔHrxn for this reaction.

b is the correct

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates

the correct answer is:

a. formation of precipitation

a corroding iron, if that's one of your choices