The hypothesis is what you think before you get your result so observations can influence your hypothesis
If you know that both glucose (C6H12O6) has same kind of atoms as ethanol (C2H6O) it is logic it is C.
Chemical (mutagens)
usually either mimic the structure of nucleotides and are inserted in DNA or either cause
chemical changes (such as alkylation) in nucleotides hence causing mismatching during replication.
Radiation, on the other hand, (due to its high energy) causes double-strand breaks in DNA causing an
increased likelihood of mutations during the repair of the DNA by cell
mechanisms.