B. Citronella aldehyde molecular formula is C10H18O, so B is wrong;

C. Isopuleol containing -OH can be eliminated, substitution reaction, carbon double bond can be added to the carbon reaction, so C is correct;

D. -CHO and carbon-carbon double bond are reacted with bromine water, and both contain double bonds, can not use bromine water to identify citronellal and isopuleol, so D is wrong;

The choice of BD.