I have a question that confuses me, any help would be appreciated. thanks
"If a solution of a substance displayed only one absorption peak, would it be safe to conclude that it was chemically pure or to conclude that there was only one light-absorbing substance present? What might be a possible alternative conclusion?"
You can't conclude very much from the absence of peaks. All you know is that no substance in the solution has an absortion peak significantly different from the one observed within the range scanned. You could have several substances with peaks that are close enough (possibly ven identical) so as not to be resolvable.