What is a good substitute for sulphuric acid?

Question

. . . for scarifying plant seeds

Answer 1

A nonchemical way is to make two sandpaper blocks and but the seed between the two and file them down.  Sometimes just nicking a corner will help.

Answer 2

Put a mask on and sneak up on them.

Answer 3

Hydrochloric acid (muriatic acid) is another strong acid that is readily available. I'm not a biologist, so I don't know whether HCl would work or not.