NEET-UG and JEE Main Chemistry · Class 12
D-L configuration; sucrose, lactose and maltose — NEET & JEE Questions
D-L configuration; sucrose, lactose and maltose is a topic in Biomolecules, a Class 12 Chemistry chapter of the NEET-UG and JEE Main syllabus. TestBudy holds 12 published NEET-UG and JEE Main questions on D-L configuration; sucrose, lactose and maltose, each with the marking scheme of the real paper.
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D-L configuration; sucrose, lactose and maltose MCQs with solutions
10 of the 12 published questions on this topic, exactly as they appear in a test. Answers and worked solutions come with your result rather than on this page.
In the Fischer projection of a monosaccharide, the D or L designation is assigned by comparing the configuration of the chiral carbon farthest from the carbonyl group with that of
- A. glyceraldehyde
- B. glucose
- C. fructose
- D. lactic acid
Which statement about D and L notation is correct?
- A. D compounds are always dextrorotatory
- B. L compounds are always levorotatory
- C. D/L notation describes relative configuration and does not by itself specify the sign of optical rotation
- D. D/L notation applies only to achiral compounds
Which disaccharide is non-reducing?
- A. Maltose
- B. Lactose
- C. Sucrose
- D. All three
Which pair of monosaccharides is obtained on hydrolysis of sucrose?
- A. Glucose and galactose
- B. Glucose and fructose
- C. Two glucose molecules
- D. Fructose and galactose
A disaccharide gives a positive reducing-sugar test and on hydrolysis yields two molecules of glucose. Which sugar is it?
- A. Sucrose
- B. Lactose
- C. Maltose
- D. Fructose
A disaccharide gives a positive reducing-sugar test and on hydrolysis yields glucose and galactose. Which sugar is it?
- A. Sucrose
- B. Lactose
- C. Maltose
- D. Trehalose
Which statement correctly compares maltose and sucrose?
- A. Both are non-reducing
- B. Maltose is reducing whereas sucrose is non-reducing
- C. Sucrose is reducing whereas maltose is non-reducing
- D. Neither can be hydrolysed
Which statement correctly identifies the monosaccharide composition of the three common disaccharides?
- A. Sucrose = glucose + fructose; lactose = galactose + glucose; maltose = glucose + glucose
- B. Sucrose = glucose + glucose; lactose = glucose + fructose; maltose = galactose + glucose
- C. Sucrose = galactose + fructose; lactose = glucose + glucose; maltose = glucose + fructose
- D. All three are made from two glucose units
A carbohydrate is classified as a D-sugar. Which conclusion is justified from this information alone?
- A. It must rotate plane-polarised light clockwise
- B. Its reference stereocentre has the D configuration relative to glyceraldehyde
- C. It must be a reducing sugar
- D. It must contain six carbon atoms
A sample contains an unknown disaccharide. It is non-reducing and hydrolysis gives two different monosaccharides, one an aldose and one a ketose. Which identification is most consistent?
- A. Maltose
- B. Lactose
- C. Sucrose
- D. Cellobiose
Common mistakes in D-L configuration; sucrose, lactose and maltose
Recorded against questions in this topic that are not shown above, so none of these points at an answer you can see on this page.
- Attributes reducing behaviour to the identity of the monosaccharides rather than availability of a free anomeric centre.
- Uses only reducing character and fails to use the hydrolysis products to distinguish lactose from maltose.
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