WAEC - Biology (2015 - No. 17)
A student used the following step in testing for a non-reducing sugar.
I. added Benedict's solution to the sugar solution
II. added dilute hydrochloric acid to the sugar solution and boiled it
III. added sodium hydroxide solution to the solution in II and boiled;
IV. added Benedict's solution to the cooled solution in III.
The colour change to be observed in step IV is
blue-black
brick-red
purple
violet
Vysvětlení
A positive test with Benedict's reagent is shown by a color change from clear blue to a brick-red precipitate.