1- Complete the following sentences: 1- Isosbestic point is 2- Pregabaline can be determined spectrophotometry after reaction with in order to 3- Alderonate can be determined spectrophotometry after reaction with in order to 4- Ferrous ions can be determined colorimetry after reaction with to produce ... 5- Requirements for ideal chromogen are ....................... \& .................. 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. ( )