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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedEasyRecall

JEE Main 25 July 2021, Shift 2, Chemistry Q49

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

Which one of the following is correct structure for cytosine ?

The figure, in words

Four drawn six-membered heterocyclic ring structures (options 3 and 4 continue on the next page).
  1. (1)[figure: six-membered ring with NH2_2 at the top vertex, ring N at upper right, a C=O at the right, N bearing H at the bottom, and a double bond on the left edge]Official answer
  2. (2)[figure: six-membered ring with H2_2N at the upper-left vertex, ring N at upper right, a C=O at the right, N bearing H at the bottom, and a double bond on the left edge]
  3. (3)[figure: six-membered ring with H3_3C at the lower-left vertex, ring N at upper right, a C=O at the right, N bearing H at the bottom, and a double bond on the left edge]
  4. (4)[figure: six-membered ring with H3_3C at the upper-left vertex, O (double bond) at the top, N-H at the upper right, a C=O at the right, N bearing H at the bottom, and a double bond on the left edge]

Official answer

Option 1

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.