A + n[O] --> produsi /.3
K2Cr2O7 + 4H2SO4 => K2SO4 + Cr2(SO4)3 + 4H2O + 3[O] / .n
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3A : nK2Cr2O7 = 1 : 1
=> 3/n = 1/1 => n = 3
alchena A va forma o cetona + acid carboxilic
deci forma alchenei A va fi
R-C(R)=CH-R