To my understanding it is water because in a real experiment session, we did use $5$ ml of ethanol to dissolve the paracetamol first then use water to dilute it to $100$ ml$,$ then we use water as blank for the UV Vis Spectroscopy. I wish to know the rationale behind this.

Why we dont straightway use $100$ml ethanol or methanol to dilute it since it is very soluble in it$.$ Why we just use small portion$(5$ml$)$ of ethanol then use distilled water to dilute it$.$ And why we don't use ethanol as blank but water?