Carbohydrates

Step 1: Meaning of reducing sugar. Reducing sugars are those carbohydrates which contain a free aldehyde group or free ketone group (through tautomerism) and can reduce Fehling's solution or Tollens' reagent.

Step 2: Analyze sucrose. Sucrose is made of glucose and fructose units. In sucrose, both anomeric carbon atoms are involved in glycosidic bond formation. Therefore no free reactive group is available.

Step 3: Analyze other options.
• Maltose: Has one free anomeric carbon, so it is reducing.
• Lactose: Also has one free anomeric carbon, so it is reducing.
• Glucose: Monosaccharide with free aldehyde form, hence reducing.

Step 4: Compare all compounds. Only sucrose does not have a free anomeric carbon atom.

Step 5: Conclusion. $ $

Step 1: Understand acetylation. During acetylation, each hydroxyl group is converted into acetate group . Net increase in mass for one hydroxyl group is: $ -OH 42u $