How anti knocking property of copression enigne can be improved

The anti-knock characteristics of a gasoline can be improved by either one of two methods. First, another fuel of higher quality can be added. This addition may be another gasoline or some compound such as alcohol, toluene, or benzol. Second, a knock suppressor1 may be added.

Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.