Case: Read the passage and answer the following qoestions

Chemically, the carbohydrates may be defined as optically active polyhydroxy aldehydes or ketones or the compounds which produce such units on hydrolysis. Some of the carbohydrates, which are sweet in taste, are also called sugars. The most common sugar, used in our homes is named sucrose whereas the sugar present in milk is known as lactose. Carbohydrates are also called saccharides (Greek: sakcharon means sugar). Carbohydrates are classified based on their behaviour on hydrolysis. They have been broadly divided into the following three groups. They are monosaccharides, oligosaccharides, and polysaccharides.