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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumDiagram reading

JEE Main 25 February 2021, Shift 2, Chemistry Q49

Question 49 of 90 in this shift, Chemistry question 19 of 30, Section A.

Which of the following is correct structure of α\alpha-anomer of maltose ?

The figure, in words

Four Haworth-type drawings, each of two six-membered rings (ring O) joined by an O bridge, with substituent labels as listed in the option text (printed labels only; positions approximate).
  1. (1)[figure: two six-membered rings (ring O at top) joined by an O bridge between the right ring-carbon of the left ring (H above) and the left ring-carbon of the right ring (H above). Left ring: H top-left, CH2OH on top, inner H and H, H on right, HO bottom-left, HO bottom, OH bottom-right. Right ring: H top-left, CH2OH on top, inner H and H, H right, H top-right, OH lower-right, HO bottom, OH bottom-right]
  2. (2)[figure: two six-membered rings (ring O at top) joined by an O bridge. Left ring: H top-left, CH2OH on top, inner H and OH, H on right, HO left, H bottom, OH bottom-right, H above the right carbon. Right ring: H top-left, CH2OH on top, inner H and OH, H, OH top-right, H lower-right, H bottom, OH bottom-right]
  3. (3)[figure: two six-membered rings (ring O at top) joined by an O bridge. Left ring: H top-left, CH2OH on top, inner H and OH, H on right, HO left, H bottom, OH bottom-right, H above the right carbon. Right ring: H top-left, CH2OH on top, inner H and OH, H, H top-right, OH lower-right, H bottom, OH bottom-right]Official answer
  4. (4)[figure: two six-membered rings (ring O at top) joined by an O bridge. Left ring: H top-left, CH2OH on top, inner H and H, H on right, HO left, OH bottom-left, OH bottom-right. Right ring: H top-left, CH2OH on top, inner H and H, H, OH top-right, H lower-right, HO bottom, OH bottom-right]

Official answer

Option 3

NTA final key.

Chapter
Biomolecules
Topic
Carbohydrates
Idea tested
Maltose Structure and Linkage

Same idea in other shifts

Asked 4× in all
  1. 27 Jun 2022, Shift 2 · Q78Given below are two statements. Statement I: Maltose has two α\alpha-D-glucose units linked at C1\mathrm{C_1} and C4\mathrm{C_4} and is a…EasyTwo statements
  2. 8 Jan 2020, Shift 2 · Q39Two monomers in maltose are :EasySingle correct
  3. 4 Sep 2020, Shift 1 · Q42What are the functional groups present in the structure of maltose ?MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.