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Friday, 9 October

JEE Main 2020 · ChemistryMultiple choiceDiagram basedMediumConceptual

JEE Main 2 September 2020, Shift 1, Chemistry Q30

Question 30 of 75 in this shift, Chemistry question 5 of 25.

The figure that is not a direct manifestation of the quantum nature of atoms is :

The figure, in words

All four options are figures (black-body intensity vs wavelength curves; photoelectron kinetic energy vs frequency lines for Rb, K, Na; internal energy of Ar vs temperature line; atomic absorption spectrum lines).
  1. (1)[figure: graph of intensity of black body radiation vs wavelength, two curves, T2 > T1 (T2 curve higher peak at shorter wavelength than T1)]
  2. (2)[figure: graph of kinetic energy of photoelectrons vs frequency of incident radiation, three parallel straight lines labelled Rb, K, Na (Rb leftmost, Na rightmost)]
  3. (3)[figure: graph of internal energy of Ar vs temperature (K) with marks 300, 400, 500, 600, a straight line rising with temperature]Official answer
  4. (4)[figure: absorption spectrum, increasing wavelength to the right, series of dark lines bunching together toward shorter wavelength]

Official answer

Option 3

NTA final key (Sep 2020).

Chapter
Structure of Atom
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 42 of the 174 JEE Main shifts held from 2017 to 2026.