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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctEasyConceptual

JEE Main 27 August 2021, Shift 1, Chemistry Q41

Question 41 of 90 in this shift, Chemistry question 11 of 30, Section A.

The gas ‘A’ is having very low reactivity reaches to stratosphere. It is non-toxic and non-flammable but dissociated by UV-radiations in stratosphere. The intermediates formed initially from the gas ‘A’ are :

The figure, in words

Each option is printed as two radical species with a dot drawn above the C (or above the O, or above the Cl) of each species; dots kept as printed.
  1. (1)C˙H3\dot{\mathrm{C}}\mathrm{H_3} + C˙F2Cl\dot{\mathrm{C}}\mathrm{F_2Cl}
  2. (2)ClO˙\mathrm{Cl}\dot{\mathrm{O}} + C˙H3\dot{\mathrm{C}}\mathrm{H_3}
  3. (3)ClO˙\mathrm{Cl}\dot{\mathrm{O}} + C˙F2Cl\dot{\mathrm{C}}\mathrm{F_2Cl}
  4. (4)Cl˙\dot{\mathrm{Cl}} + C˙F2Cl\dot{\mathrm{C}}\mathrm{F_2Cl}Official answer

Official answer

Option 4

NTA final key.

Chapter
Environmental Chemistry
Topic
Environmental Chemistry
Idea tested
Ozone Layer Depletion

Same idea in other shifts

Asked 8× in all
  1. 8 Apr 2023, Shift 2 · Q70Which of these reactions is not a part of breakdown of ozone in stratosphere?MediumSingle correct
  2. 11 Apr 2023, Shift 2 · Q71Which of the following compounds is an example of Freon?EasySingle correct
  3. 13 Apr 2023, Shift 1 · Q72The radical which mainly causes ozone depletion in the presence of UV radiations is :EasySingle correct
  4. 26 Jul 2022, Shift 1 · Q70C˙l+CH4→A+B\dot{\mathrm{C}}\mathrm{l} + \mathrm{CH_4} \rightarrow \mathrm{A} + \mathrm{B} A and B in the above atmospheric reaction step are :EasySingle correct
  5. 4 Aug 2021, Shift 1 · Q41In stratosphere, chlorofluorocarbon compounds break down by UV radiations, releasing 'X' free radical, which further causes ozone layer…EasySingle correct
  6. 25 Jul 2021, Shift 2 · Q41Given below are two statements : Statement I : Chlorofluoro carbons breakdown by radiation in the visible energy region and release…MediumTwo statements
  7. 2 Sep 2020, Shift 1 · Q38The statement that is not true about ozone is :EasySingle 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.