According to Merriam-Webster: Definition of tonite. : a blasting explosive consisting of a mixture of guncotton with a nitrate and sometimes a nitro compound.
Collins dictionary: Tonite definition: an explosive used in quarrying.
I'm pretty sure this is not what you have in mind. Also, Duolingo is an American company and it promotes (and requires) embracing differences from its users. You may want to read more here.