Target Exam

CUET

Subject

Chemistry

Chapter

Physical: Chemical Kinetics

Question:

Read the passage carefully and answer the questions.

Carbohydrates are naturally formed organic compounds from various plants. The common chemical formula, $(C_x(H_2O)_y)$ was considered as hydrates of carbon to derive the various carbohydrates. For instance, the general formula for glucose $(C_6H_{12}O_6)$ easily fits into the above formula. Carbohydrates also called saccharides are classified on the basis of their behavior towards hydrolysis. Monosaccharides cannot be hydrolyzed further to simpler units of polyhydroxy aldehyde or ketones. About 20 monosaccharides are known to occur in nature. Carbohydrates that yield large number of monosaccharide units are called polysacccharides. Amino acids contain $(-NH_2)$ and $(-COOH)$, which can be classified in various forms. Proteins are polymers of alpha amino acids which are connected to each other by a peptide bond or peptide linkage. When a native protein is subjected to physical change, its globules unfold and helix get uncoiled and the protein loses its biological activity. The protein is said to be denaturated.

Which of the following statements is incorrect for Lactose?

Options:

Lactose is a reducing sugar

It is known as milk sugar

On hydrolysis it yields galactose and glucose

It is an invert sugar

Correct Answer:

It is an invert sugar

Explanation:

The correct answer is Option (4) → It is an invert sugar **

Let's analyze each statement about lactose:

  1. Lactose is a reducing sugar ✅ – True, because the glucose unit has a free anomeric carbon.
  2. It is known as milk sugar ✅ – True, lactose is the main sugar in milk.
  3. On hydrolysis it yields galactose and glucose ✅ – True.
  4. It is an invert sugar ❌ – False, invert sugar refers to sucrose, which gives a mixture of glucose and fructose that rotates plane-polarized light. Lactose does not give invert sugar on hydrolysis.