Q1.
Does the water taste sweet?
Answer
Before stirring — no, or at most very faintly.
The sugar has just been dropped in and, being denser than water, it lies as a heap at the bottom of the tumbler. Only a little of it has begun to dissolve, and those particles are still down near the bottom. A spoonful taken from the top layer therefore tastes like ordinary drinking water.
Wait long enough and this changes. Even without stirring, the water particles are in constant motion and would slowly carry the sugar particles all the way to the top — the same spreading you watch in Activity 7.8 with potassium permanganate. Stirring only makes it fast.
Safety first: perform this activity under the supervision of a teacher or an adult, and never eat or drink anything in the laboratory unless you are asked to.