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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceDiagram basedMediumDiagram reading

JEE Main 9 January 2020, Shift 1, Physics Q7

Question 7 of 75 in this shift, Physics question 7 of 25, Section A.

Which of the following is an equivalent cyclic process corresponding to the thermodynamic cyclic given in the figure ? where, 1→21 \rightarrow 2 is adiabatic. (Graphs are schematic and are not to scale)

The figure, in words

P (vertical axis) versus V (horizontal axis) graph with three points: 1 at the top left, 2 at the right on the same horizontal level as 3, and 3 at the bottom left directly below 1. A curve from 1 down to 2 with arrow pointing towards 2 (from 1 to 2); a horizontal line from 2 to 3 with arrow pointing left (towards 3); a vertical line from 3 up to 1 with arrow pointing up (towards 1).
  1. (1)[figure: V (vertical axis) versus T (horizontal axis) graph; point 3 at lower left and point 1 at lower right joined by a horizontal line with arrow pointing right (3 to 1); point 2 at the top; a slightly curved line from 1 up to 2 with arrow pointing towards 2; a straight line from 2 down to 3 with arrow pointing towards 3]Official answer
  2. (2)[figure: V (vertical axis) versus T (horizontal axis) graph; point 2 at upper left, point 1 at lower right, point 3 slightly right of the bottom of the left side; a curve from 1 up to 2 with arrow pointing towards 2; a steep curve from 2 down to 3 with arrow pointing towards 3; a short horizontal line from 3 to 1 with arrow pointing right]
  3. (3)[figure: V (vertical axis) versus T (horizontal axis) graph; points 3 and 2 at the top left joined by a horizontal line with arrow pointing left (2 to 3); point 1 at the right at lower height; a steep curve from 1 up to 2 with arrow pointing towards 2; a curve from 3 down and to the right to 1 with arrow pointing right/towards 1]
  4. (4)[figure: V (vertical axis) versus T (horizontal axis) graph; triangle of straight lines; point 3 at lower left and point 1 at lower right joined by a horizontal line with arrow pointing right; point 2 at the top; line from 1 to 2 with arrow pointing towards 2; line from 2 to 3 with arrow pointing towards 3]

Official answer

Option 1

NTA final key (Jan 2020).

Chapter
Thermodynamics
Topic
Thermodynamic Processes
Idea tested
Indicator Diagram Conversions

Same idea in other shifts

Asked 3× in all
  1. 17 Mar 2021, Shift 2 · Q19Which one is the correct option for the two different thermodynamic processes ?MediumDiagram basedHas a figure
  2. 8 Jan 2020, Shift 1 · Q8A thermodynamic cycle xyzxxyzx is shown on a V-T diagram. The P-V diagram that best describes this cycle is : (Diagrams are schematic and…MediumDiagram 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.