Learn

Saturday, 31 October

JEE Main 2024 · ChemistryMultiple choiceDiagram basedMediumDiagram reading

JEE Main 6 April 2024, Shift 1, Chemistry Q80

Question 80 of 90 in this shift, Chemistry question 20 of 30, Section A.

DNA molecule contains 4 bases whose structure are shown below. One of the structures is not correct, identify the incorrect base structure.

The figure, in words

Four drawn nucleobase structures as options; no stem figure.
  1. (1)[figure: purine base with NH2 at top right (adenine-type); ring atoms HC=N, NH, N=CH]
  2. (2)[figure: purine base with H3C–C on left, C=O at top, NH, and NH2 at bottom right (guanine-type with a methyl group)]Official answer
  3. (3)[figure: pyrimidine base with NH2, HC=HC, N–H and C=O (cytosine-type)]
  4. (4)[figure: pyrimidine base with H3C–C, C=O, NH, C=O and N–H (thymine-type)]

Official answer

Option 2

NTA final key.

Chapter
Biomolecules
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.