weak acids

[professor]

i had this question on atest recently, it said to identify whish of these is not a weak acid: HCNO : HBr : HF : HNO2 : HCN. Now the problem i am having with his, is in my book it gives that theyre common acids...ig deal, not if theyre strong or weak, and on the internet as far as i have found theyre all weak acids. This puzzles me greatly. I can tell you one more thing, the one i hadent seen enough to be sure (HCNO) definetly isent it, because thats the one i put down, and it was marked wrong.

[TRCSF]

HBr is the correct answer.

Usually in chemistry textbooks they give you a table of six strong acids. HBr, HCl, HI, H2SO4, H3PO4, and HNO3. Double check your notes and book. It's probably in there.

[professor]

thats what i was starting to lean towards, though i fugured it might have been hf too because of flourine's strong electronegativity, then i did look that up though an was disprooved fairly quickly.

[TRCSF]

Yeah, you wouldn't be the first chemistry student to think that.

Fluorine's a tricky little bastard that's no good to anybody.