II- Give reason for the following sentences: 1- Spectrophotometric determination must be made in a buffered solution. 2. Spectrophotometric determination must be made at isosbestic point. (the same answer) III- Write () or (X) : 1- At isosbestic point absorbance is pH dependent. ( ) 2- Derivatization increase the sensitivity, and not increase selectivity of the analysis. ( )