Learn

Saturday, 31 October

JEE Main 2026 · ChemistryMultiple choiceDiagram basedMediumMulti-step

JEE Main 4 April 2026, Shift 2, Chemistry Q68

Question 68 of 75 in this shift, Chemistry question 18 of 25, Section A.

A D-aldotetrose on oxidation with concentrated HNO3\mathrm{HNO_3} resulted in optically inactive dicarboxylic acid. The structure of the D-aldotetrose is:

The figure, in words

Options are Fischer projections of aldotetroses (CHO at top, CH2OH at bottom, two stereocentres).
  1. (1)[figure: Fischer projection, CHO top, C2: HO left / H right, C3: HO left / H right, CH2OH bottom]
  2. (2)[figure: Fischer projection, CHO top, C2: H left / OH right, C3: HO left / H right, CH2OH bottom]
  3. (3)[figure: Fischer projection, CHO top, C2: H left / OH right, C3: H left / OH right, CH2OH bottom]Official answer
  4. (4)[figure: Fischer projection, CHO top, C2: HO left / H right, C3: H left / OH right, CH2OH bottom]

Official answer

Option 3

NTA final key.

Chapter
Biomolecules
Topic
Carbohydrates
Idea tested
Selective Oxidation of Monosaccharides

Same idea in other shifts

Asked 4× in all
  1. 8 Apr 2024, Shift 1 · Q80The incorrect statement regarding the given structure is [figure: Fischer projection: CHO at top; then H-C-OH, HO-C-H, H-C-OH, H-C-OH;…MediumDiagram basedHas a figure
  2. 31 Jan 2024, Shift 1 · Q79Match List I with List II LIST I A. Glucose/NaHCO3\mathrm{NaHCO_3}/Δ\Delta B. Glucose/HNO3\mathrm{HNO_3} C. Glucose/HI/Δ\Delta D.…MediumMatch the list
  3. 27 Jun 2022, Shift 1 · Q79L-isomer of a compound ‘A’ (C4H8O4\mathrm{C_4H_8O_4}) gives a positive test with [Ag(NH3)2]+\mathrm{[Ag(NH_3)_2]^+}. Treatment of ‘A’ with acetic…HardDiagram basedHas a figure

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.