history word misspelt

i have written carbonic acid instead of carbolic acid how many marks do i loose

If this is for a history essay, like the title suggests, I imagine the person marking your exam probably won’t take much notice of it. The worst that I can imagine would happen is that it may lower a spelling, punctuation and grammar mark very slightly if that is part of the marking criteria.

If this was a chemistry exam, like the forum this has been posted in suggests, you’d be penalised more harshly (in chemistry, the preferred name for carbolic acid is ‘phenol’, but that’s besides the point).