JEE Main 2021 Question Paper & Answers
The official JEE Main 2021 question paper, with the official answer key. Attempt as a real timed exam (with negative marking) or switch to practice mode for instant per-question answers and explanations.
🔓 No sign-in needed to attempt a paper and see your score.
Official PYQ
JEE Main 2021 - February 26 Shift 1
180 Mins 300 Marks
75Questions
300Max Marks
Sample questions from JEE Main 2021 - February 26 Shift 1
1If and are the wavelengths of the third member of the Lyman series and the first member of the Paschen series respectively, then the value of is:
- A) 1:3
- B) 1:9
- C) 7:135
- D) 7:108
Answer: C
2The temperature at the junction of two insulating sheets, having thermal resistances and , as well as top and bottom temperatures and respectively, is given by:
- A)
- B)
- C)
- D)
Answer: A
3In a Young's double slit experiment, two slits are separated by 2 mm and the screen is placed one metre away. When light of wavelength 500 nm is used, the fringe separation will be:
- A) 0.75 mm
- B) 0.50 mm
- C) 1 mm
- D) 0.25 mm
Answer: D
4Given below are two statements, one labelled as Assertion A and the other labelled as Reason R.
Assertion A: An electron microscope can achieve better resolving power than an optical microscope.
Reason R: The de Broglie wavelength of the electrons emitted from an electron gun is much less than the wavelength of visible light.
Choose the correct answer:
- A) A is true but R is false.
- B) Both A and R are true but R is NOT the correct explanation of A.
- C) Both A and R are true and R is the correct explanation of A.
- D) A is false but R is true.
Answer: C
5Four identical solid spheres, each of mass and radius , are placed with their centres on the four corners of a square of side . The moment of inertia of the system about one side of the square, where the axis of rotation is parallel to the plane of the square, is:
- A)
- B)
- C)
- D)
Answer: D
+70 more questions — attempt the full paper to see them all.