I dont know this....please help

Question

ok first of all what is a representative particle????

ok and second is how many oxygen atoms are in 10 formula units of Al2(SO4)3

Answer 1

what is a representative particle????

it sounds like someone is trying to be generic, without telling you if you have a compound , or an element

the representative particle of an element is an "atom"

the representative particle of an compound is a "molecule"

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ok and second is how many oxygen atoms are in 10 formula units of Al2(SO4)3

SO4 has four oxygens, (SO4)3 has twelve oxygens, 10 Al2(SO4)3 has 120 oxygens

youi answer is 120 oxygens