JEE Main 2021 February 25 Shift 2 Question Paper is available here with solutions PDF and detailed solutions for every question. NTA conducted the second shift on February 25, 2021, from 3:00 PM to 6:00 PM. The JEE Main 2021 Paper 1 (B.E./B.Tech) question paper includes the following:

  • 90 questions in a 3-hour CBT Mode: 30 each from Mathematics, Physics and Chemistry (75 to be attempted)
  • Section A: 20 multiple choice questions (MCQs) per subject, all compulsory, 4 marks each
  • Section B: 10 numerical value questions per subject, any 5 to be attempted, 4 marks each
  • Marking: +4 for a correct answer, -1 for an incorrect MCQ, 0 for an unattempted question; no negative marking for numerical value questions
  • Maximum marks: 300 (100 per subject)

JEE Main 2021 February 25 Shift 2 Question Paper with Solution PDF

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JEE Main 2021 February 25 Shift 2 Questions with Solutions


Mathematics - Section A (Q1 - Q20)

Question 1:

The shortest distance between the line \(x-y=1\) and the curve \(x^2 = 2y\) is:

  • (1) \(\frac{1}{\sqrt{2}}\)
  • (2) \(\frac{1}{2\sqrt{2}}\)
  • (3) 0
  • (4) \(\frac{1}{2}\)

Question 2:

A function f(x) is given by f(x) = \(\frac{5^x}{5^x + 5}\), then the sum of the series \(f(\frac{1}{20}) + f(\frac{2}{20}) + \dots + f(\frac{39}{20})\) is equal to:

  • (1) \(\frac{29}{2}\)
  • (2) \(\frac{49}{2}\)
  • (3) \(\frac{39}{2}\)
  • (4) \(\frac{19}{2}\)

Question 3:

Let x denote the total number of one-one functions from a set A with 3 elements to a set B with 5 elements and y denote the total number of one-one functions from the set A to the set A \(\times\) B. Then :

  • (1) 2y = 91x
  • (2) 2y = 273x
  • (3) y = 91x
  • (4) y = 273x

Question 4:

The integral \(\int \frac{e^{3\log_e{2x}} + 5e^{2\log_e{2x}}}{e^{4\log_e{x}} + 5e^{3\log_e{x}} - 7e^{2\log_e{x}}} \,dx\), x>0, is equal to: (where c is a constant of integration)

  • (1) \(\log_e |x^2+5x-7| + c\)
  • (2) \(4\log_e |x^2+5x-7| + c\)
  • (3) \(\frac{1}{4}\log_e |x^2+5x-7| + c\)
  • (4) \(\log_e \sqrt{x^2+5x-7} + c\)

Question 5:

Let A be a set of all 4-digit natural numbers whose exactly one digit is 7. Then the probability that a randomly chosen element of A leaves remainder 2 when divided by 5 is :

  • (1) \(\frac{1}{5}\)
  • (2) \(\frac{2}{9}\)
  • (3) \(\frac{97}{297}\)
  • (4) \(\frac{122}{297}\)

Question 6:

Let \(\alpha\) and \(\beta\) be the roots of \(x^2 - 6x - 2 = 0\). If \(a_n = \alpha^n - \beta^n\) for \(n \ge 1\), then the value of \(\frac{a_{10} - 2a_8}{3a_9}\) is:

  • (1) 4
  • (2) 3
  • (3) 2
  • (4) 1

Question 7:

 if 0<x, y<\(\pi\) and cosx+cosy-cos(x y)=\(\frac{3}{2}\),Then sin x+cos y=?
 

  • (1) \(\frac{1}{2}\)
  • (2) \(\frac{1+\sqrt3}{2}\)
  • (3) \(\frac{\sqrt3}{2}\)
  • (4) \(\frac{1-\sqrt3}{2}\)

Question 8:

cosec[2cot\(^{-1}\)(5) + cos\(^{-1}\)(\(\frac{4}{5}\))] is equal to :

  • (1) \(\frac{56}{33}\)
  • (2) \(\frac{65}{33}\)
  • (3) \(\frac{65}{56}\)
  • (4) \(\frac{75}{56}\)

Question 9:

Let A be a 3\(\times\)3 matrix with det(A)=4. Let R\(_i\) denote the i\(^{th}\) row of A. If a matrix B is obtained by performing the operation R\(_2\) \(\rightarrow\) 2R\(_2\)+5R\(_3\) on 2A, then det(B) is equal to:

  • (1) 80
  • (2) 64
  • (3) 128
  • (4) 16

Question 10:

If \(\alpha, \beta \in R\) are such that 1\(-\)2i (here \(i^2\)=\(-\)1) is a root of z\(^2\)+\(\alpha\)z+\(\beta\)=0, then (\(\alpha-\beta\)) is equal to:

  • (1) 3
  • (2) -3
  • (3) 7
  • (4) -7

Question 11:

The minimum value of f(x) = \(a^{a^x} + a^{1-a^x}\), where a, x \(\in\) R and a>0, is equal to :

  • (1) a + 1
  • (2) a + \(\frac{1}{a}\)
  • (3) 2a
  • (4) 2\(\sqrt{a}\)

Question 12:

If I\(_n\) = \(\int_{\pi/4}^{\pi/2} \cot^n x \,dx\), then :

  • (1) \(\frac{1}{I_2+I_4}, \frac{1}{I_3+I_5}, \frac{1}{I_4+I_6}\) are in A.P.
  • (2) \(I_2+I_4, I_3+I_5, I_4+I_6\) are in A.P.
  • (3) \(\frac{1}{I_2+I_4}, \frac{1}{I_3+I_5}, \frac{1}{I_4+I_6}\) are in G.P.
  • (4) \(I_2+I_4, (I_3+I_5)^2, I_4+I_6\) are in G.P.

Question 13:

In a group of 400 people, 160 are smokers and non-vegetarian; 100 are smokers and vegetarian and the remaining 140 are non-smokers and vegetarian. Their chances of getting a particular chest disorder are 35%, 20% and 10% respectively. A person is chosen from the group at random and is found to be suffering from the chest disorder. The probability that the selected person is a smoker and non-vegetarian is:

  • (1) \(\frac{7}{45}\)
  • (2) \(\frac{8}{45}\)
  • (3) \(\frac{28}{45}\)
  • (4) \(\frac{14}{45}\)

Question 14:

If for the matrix, A = \( A = \begin{bmatrix} 1 & -\alpha \\ \alpha & \beta \end{bmatrix} \), and \( A A^T = I_2 \), then the value of \( \alpha^4 + \beta^4 \) is :

  • (1) 4
  • (2) 1
  • (3) 2
  • (4) 3

Question 15:

If the curve \(x^2+2y^2 = 2\) intersects the line \(x+y=1\) at two points P and Q, then the angle subtended by the line segment PQ at the origin is :

  • (1) \(\frac{\pi}{2} + \tan^{-1}(\frac{1}{4})\)
  • (2) \(\frac{\pi}{2} - \tan^{-1}(\frac{1}{4})\)
  • (3) \(\frac{\pi}{2} + \tan^{-1}(\frac{1}{3})\)
  • (4) \(\frac{\pi}{2} - \tan^{-1}(\frac{1}{3})\)

Question 16:

The following system of linear equations
2x + 3y + 2z = 9
3x + 2y + 2z = 9
x - y + 4z = 8

  • (1) does not have any solution
  • (2) has a unique solution
  • (3) has infinitely many solutions
  • (4) has a solution (\(\alpha, \beta, \gamma\)) satisfying \(\alpha + \beta^2 + \gamma^2 = 12\)

Question 17:

A hyperbola passes through the foci of the ellipse \(\frac{x^2}{25} + \frac{y^2}{16} = 1\) and its transverse and conjugate axes coincide with major and minor axes of the ellipse, respectively. If the product of their eccentricities is one, then the equation of the hyperbola is:

  • (1) \(\frac{x^2}{9} - \frac{y^2}{16} = 1\)
  • (2) \(\frac{x^2}{9} - \frac{y^2}{4} = 1\)
  • (3) \(\frac{x^2}{9} - \frac{y^2}{25} = 1\)
  • (4) \(x^2 - y^2 = 9\)

Question 18:

\(\lim_{n\to\infty} [\frac{1}{n} + \frac{n}{(n+1)^2} + \frac{n}{(n+2)^2} + \dots + \frac{n}{(2n-1)^2}]\) is equal to :

  • (1) 1
  • (2) \(\frac{1}{2}\)
  • (3) \(\frac{1}{3}\)
  • (4) \(\frac{1}{4}\)

Question 19:

The contrapositive of the statement "If you will work, you will earn money" is:

  • (1) To earn money, you need to work
  • (2) You will earn money, if you will not work
  • (3) If you will not earn money, you will not work
  • (4) If you will earn money, you will work

Question 20:

A plane passes through the points A(1, 2, 3), B(2, 3, 1) and C(2, 4, 2). If O is the origin and P is (2, -1, 1), then the projection of \(\vec{OP}\) on this plane is of length :

  • (1) \(\sqrt{\frac{2}{3}}\)
  • (2) \(\sqrt{\frac{2}{11}}\)
  • (3) \(\sqrt{\frac{2}{7}}\)
  • (4) \(\sqrt{\frac{2}{5}}\)

Mathematics - Section B (Q21 - Q30)

Question 21:

If the remainder when x is divided by 4 is 3, then the remainder when \((2020+x)^{2022}\) is divided by 8 is ________ .


Question 22:

The total number of two digit numbers 'n', such that \(3^n + 7^n\) is a multiple of 10, is ________ .


Question 23:

The value of \(\int_{-2}^{2} |3x^2-3x-6| \,dx\) is ________ .


Question 24:

A line 'l' passing through origin is perpendicular to the lines
\(l_1: \vec{r} = (3+t)\hat{i} + (-1+2t)\hat{j} + (4+2t)\hat{k}\)
\(l_2: \vec{r} = (3+2s)\hat{i} + (3+2s)\hat{j} + (2+s)\hat{k}\)
If the co-ordinates of the point in the first octant on \(l_2\) at a distance of \(\sqrt{17}\) from the point of intersection of 'l' and '\(l_1\)' are (a, b, c), then 18(a+b+c) is equal to ________ .


Question 25:

A function \( f \) is defined on \([-3, 3]\) as \( f(x) = \begin{cases} \min\{|x|, 2-x^2\}, & -2 \le x \le 2 \\ |x|, & 2 < |x| \le 3 \end{cases} \), where \( [x] \) denotes the greatest integer \( \le x \). The number of points, where \( f \) is not differentiable in \((-3, 3)\) is ________ .


Question 26:

Let \(\vec{a} = \hat{i} + \alpha\hat{j} + 3\hat{k}\) and \(\vec{b} = 3\hat{i} - \alpha\hat{j} + \hat{k}\). If the area of the parallelogram whose adjacent sides are represented by the vectors \(\vec{a}\) and \(\vec{b}\) is 8\(\sqrt{3}\) square units, then \(\vec{a} \cdot \vec{b}\) is equal to ________ .


Question 27:

If lim\(_{x\to 0} \frac{ax - (e^{4x}-1)}{ax(e^{4x}-1)}\) exists and is equal to b, then the value of a\(-\)2b is ________ .


Question 28:

If the curve, y=y(x) represented by the solution of the differential equation \((2xy^2-y)dx+xdy=0\), passes through the intersection of the lines, 2x\(-\)3y=1 and 3x+2y=8, then \(|y(1)|\) is equal to ________ .


Question 29:

If the curves \(x=y^4\) and \(xy=k\) cut at right angles, then \((4k)^6\) is equal to ________ .


Question 30:

A line is a common tangent to the circle \((x-3)^2+y^2=9\) and the parabola \(y^2=4x\). If the two points of contact (a, b) and (c, d) are distinct and lie in the first quadrant, then 2(a+c) is equal to ________ .


Physics - Section A (Q31 - Q50)

Question 31:

An LCR circuit contains resistance of 110 \(\Omega\) and a supply of 220 V at 300 rad/s angular frequency. If only capacitance is removed from the circuit, current lags behind the voltage by 45°. If on the other hand, only inductor is removed the current leads by 45° with the applied voltage. The rms current flowing in the circuit will be:

  • (1) 1 A
  • (2) 1.5 A
  • (3) 2 A
  • (4) 2.5 A

Question 32:

An electron with kinetic energy \(K_1\) enters between parallel plates of a capacitor at an angle '\(\alpha\)' with the plates. It leaves the plates at angle '\(\beta\)' with kinetic energy \(K_2\). Then the ratio of kinetic energies \(K_1 : K_2\) will be:

  • (1) \(\frac{\cos\beta}{\cos\alpha}\)
  • (2) \(\frac{\cos\beta}{\sin\alpha}\)
  • (3) \(\frac{\sin^2\beta}{\cos^2\alpha}\)
  • (4) \(\frac{\cos^2\beta}{\cos^2\alpha}\)

Question 33:

A sphere of radius 'a' and mass 'm' rolls along a horizontal plane with constant speed \(v_0\). It encounters an inclined plane at angle \(\theta\) and climbs upward. Assuming that it rolls without slipping, how far up the sphere will travel? 

 

  • (1) \(\frac{v_0^2}{2g \sin\theta}\)
  • (2) \(\frac{v_0^2}{5g \sin\theta}\)
  • (3) \(\frac{10v_0^2}{7g \sin\theta}\)
  • (4) (Incomplete in source)

Question 34:

An electron of mass \(m_e\) and a proton of mass \(m_p = 1836 m_e\) are moving with the same speed. The ratio of their de Broglie wavelength \(\frac{\lambda_{electron}}{\lambda_{proton}}\) will be:

  • (1) 1
  • (2) 1836
  • (3) \(\frac{1}{1836}\)
  • (4) 918

Question 35:

Consider the diffraction pattern obtained from the sunlight incident on a pinhole of diameter 0.1 \(\mu\)m. If the diameter of the pinhole is slightly increased, it will affect the diffraction pattern such that:

  • (1) its size increases, and intensity increases
  • (2) its size increases, but intensity decreases
  • (3) its size decreases, but intensity increases
  • (4) its size decreases, and intensity decreases

Question 36:

In a ferromagnetic material, below the curie temperature, a domain is defined as:

  • (1) a macroscopic region with zero magnetization.
  • (2) a macroscopic region with saturation magnetization.
  • (3) a macroscopic region with randomly oriented magnetic dipoles.
  • (4) a macroscopic region with consecutive magnetic dipoles oriented in opposite direction.

Question 37:

Given below are two statements:
Statement I: In a diatomic molecule, the rotational energy at a given temperature obeys Maxwell's distribution.
Statement II: In a diatomic molecule, the rotational energy at a given temperature equals the translational kinetic energy for each molecule.

  • (1) Both Statement I and Statement II are true.
  • (2) Both Statement I and Statement II are false.
  • (3) Statement I is true but Statement II is false.
  • (4) Statement I is false but Statement II is true.

Question 38: Match List I with List II.
List IList II
(a)Rectifier(i)Used either for stepping up or stepping down the a.c. voltage
(b)Stabilizer(ii)Used to convert a.c. voltage into d.c. voltage
(c)Transformer(iii)Used to remove any ripple in the rectified output voltage
(d)Filter(iv)Used for constant output voltage even when the input voltage or load current change

Choose the correct answer from the options given below :
  • (1) (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
  • (2) (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
  • (3) (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
  • (4) (a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)

Question 39:

A charge 'q' is placed at one corner of a cube as shown in figure. The flux of electrostatic field \(\vec{E}\) through the shaded area is: 

 

  • (1) \(\frac{q}{4\epsilon_0}\)
  • (2) \(\frac{q}{8\epsilon_0}\)
  • (3) \(\frac{q}{24\epsilon_0}\)
  • (4) (Option seems to be missing from OCR)

Question 40:

Thermodynamic process is shown below on a P-V diagram for one mole of an ideal gas. If \(V_2=2V_1\) then the ratio of temperature \(T_2/T_1\) is: The process is \(PV^{1/2}\) = constant. 

 

  • (1) \(\frac{1}{\sqrt{2}}\)
  • (2) \(\sqrt{2}\)
  • (3) \(\frac{1}{2}\)
  • (4) 2

Question 41:

The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n=2 to n=1 state is:

  • (1) 121.8 nm
  • (2) 194.8 nm
  • (3) 490.7 nm
  • (4) 913.3 nm

Question 42:

Y = A sin(\(\omega\)t+\(\phi_0\)) is the time-displacement equation of a SHM. At t = 0 the displacement of the particle is Y = \(\frac{A}{2}\) and it is moving along negative x-direction. Then the initial phase angle \(\phi_0\) will be:

  • (1) \(\frac{\pi}{3}\)
  • (2) \(\frac{5\pi}{6}\)
  • (3) \(\frac{\pi}{6}\)
  • (4) \(\frac{2\pi}{3}\)

Question 43:

Two identical springs of spring constant '2k' are attached to a block of mass m and to fixed support (see figure). When the mass is displaced from equilibrium position on either side, it executes simple harmonic motion. The time period of oscillations of this system is: 

 

  • (1) \(2\pi\sqrt{\frac{m}{2k}}\)
  • (2) \(2\pi\sqrt{\frac{m}{k}}\)
  • (3) \(\pi\sqrt{\frac{m}{k}}\)
  • (4) \(\pi\sqrt{\frac{m}{2k}}\)

Question 44:

The point A moves with a uniform speed along the circumference of a circle of radius 0.36 m and covers 30° in 0.1 s. The perpendicular projection 'P' from 'A' on the diameter MN represents the simple harmonic motion of 'P'. The restoration force per unit mass when P touches M will be: 

  • (1) 100 N
  • (2) 9.87 N
  • (3) 50 N
  • (4) 0.49 N

Question 45:

If e is the electronic charge, c is the speed of light in free space and h is Planck's constant, the quantity \(\frac{1}{4\pi\epsilon_0}\frac{e^2}{hc}\) has dimensions of:

  • (1) \([M L T⁰]\)
  • (2) \([M L T⁻¹]\)
  • (3) \([M⁰ L⁰ T⁰]\)
  • (4) \([L C⁻¹]\)

Question 46:

For extrinsic semiconductors; when doping level is increased;

  • (1) Fermi-level of p-type semiconductor will go upward and Fermi-level of n-type semiconductors will go downward.
  • (2) Fermi-level of p-type semiconductors will go downward and Fermi-level of n-type semiconductor will go upward.
  • (3) Fermi-level of p and n-type semiconductors will not be affected.
  • (4) Fermi-level of both p-type and n-type semiconductors will go upward for T>\(T_F\) K and downward for T<\(T_F\) K, where \(T_F\) is Fermi temperature.

Question 47:

The truth table for the following logic circuit is: 


 

  • (1) A
  • (2) B
  • (3) C
  • (4) D

Question 48:

A stone is dropped from the top of a building. When it crosses a point 5 m below the top, another stone starts to fall from a point 25 m below the top. Both stones reach the bottom simultaneously. The height of the building is:

  • (1) 45 m
  • (2) 25 m
  • (3) 35 m
  • (4) 50 m

Question 49:

The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength 491 nm is 0.710 V. When the incident wavelength is changed to a new value, the stopping potential is 1.43 V. The new wavelength is:

  • (1) 309 nm
  • (2) 329 nm
  • (3) 382 nm
  • (4) 400 nm

Question 50:

If a message signal of frequency '\(f_m\)' is amplitude modulated with a carrier signal of frequency '\(f_c\)' and radiated through an antenna, the wavelength of the corresponding signal in air is:

  • (1) \(\frac{c}{f_c - f_m}\)
  • (2) \(\frac{c}{f_c + f_m}\)
  • (3) \(\frac{c}{f_c}\)
  • (4) \(\frac{c}{f_m}\)

Physics - Section B (Q51 - Q60)

Question 51:

If \(\vec{P} \times \vec{Q} = \vec{Q} \times \vec{P}\), the angle between \(\vec{P}\) and \(\vec{Q}\) is \(\theta\) (0°<\(\theta\)<360°). The value of '\(\theta\)' will be ________°.


Question 52:

The percentage increase in the speed of transverse waves produced in a stretched string if the tension is increased by 4 percent , will be ________ . 
 


Question 53:

The initial velocity \(v_i\) required to project a body vertically upward from the surface of the earth to reach a height of 10R, where R is the radius of the earth, may be described in terms of escape velocity \(v_e\) such that \(v_i = \sqrt{\frac{x}{11}} v_e\). The value of x will be ________ .


Question 54:

The peak electric field produced by the radiation coming from the 8 W bulb at a distance of 10 m is \(\frac{x}{10} \sqrt{\frac{\mu_0 c}{\pi}} \frac{V}{m}\). The efficiency of the bulb is 10% and it is a point source. The value of x is ________ .


Question 55:

Two identical conducting spheres with negligible volume have 2.1 nC and –0.1 nC charges, respectively. They are brought into contact and then separated by a distance of 0.5 m. The electrostatic force acting between the spheres is ________ \(\times\) 10⁻⁹ N. [Given : \(4\pi\epsilon_0 = \frac{1}{9 \times 10^9}\) SI unit]


Question 56:

The wavelength of an X-ray beam is 10 Å. The mass of a fictitious particle having the same energy as that of the X-ray photons is \(\frac{x}{3}h\) kg. The value of x is ________ . (h=Planck's constant)


Question 57:

Two small spheres each of mass 10 mg are suspended from a point by threads 0.5 m long. They are equally charged and repel each other to a distance of 0.20 m. The charge on each of the sphere is \(\frac{a}{21} \times 10^{-8} C\). 
The value of 'a' will be ______. [Given g = 10 ms–2]


Question 58:

Two particles having masses 4 g and 16 g respectively are moving with equal kinetic energies. The ratio of the magnitudes of their linear momentum is n : 2. The value of n will be ________ .


Question 59:

A current of 6 A enters one corner P of an equilateral triangle PQR having 3 wires of resistance 2 \(\Omega\) each and leaves by the corner R. The currents \(i_1\) in ampere is ________ . 


Question 60:

A reversible heat engine converts one-fourth of the heat input into work. When the temperature of the sink is reduced by 52 K, its efficiency is doubled. The temperature in Kelvin of the source will be ________ .


Chemistry - Section A (Q61 - Q80)

Question 61:

The correct sequence of reagents used in the preparation of 4-bromo-2-nitroethylbenzene from benzene is:

  • (1) CH\(_3\)COCl/AlCl\(_3\), Br\(_2\)/AlBr\(_3\), HNO\(_3\)/H\(_2\)SO\(_4\), Zn/HCl
  • (2) CH\(_3\)COCl/AlCl\(_3\), Zn-Hg/HCl, Br\(_2\)/AlBr\(_3\), HNO\(_3\)/H\(_2\)SO\(_4\)
  • (3) Br\(_2\)/AlBr\(_3\), CH\(_3\)COCl/AlCl\(_3\), HNO\(_3\)/H\(_2\)SO\(_4\), Zn/HCl
  • (4) HNO\(_3\)/H\(_2\)SO\(_4\), Br\(_2\)/AlCl\(_3\), CH\(_3\)COCl/AlCl\(_3\), Zn-Hg/HCl

Question 62:

What is 'X' in the given reaction?

  • (1)
  • (2)
  • (3)
  • (4)

Question 63:

The solubility of Ca(OH)\(_2\) in water is:
[Given: The solubility product of Ca(OH)\(_2\) in water = 5.5 \(\times\) 10⁻⁶]

  • (1) 1.11 \(\times\) 10⁻²
  • (2) 1.11 \(\times\) 10⁻⁶
  • (3) 1.77 \(\times\) 10⁻²
  • (4) 1.77 \(\times\) 10⁻⁶

Question 64:

Which among the following species has unequal bond lengths?

  • (1) XeF\(_4\)
  • (2) SiF\(_4\)
  • (3) SF\(_4\)
  • (4) BF\(_4^-\)

Question 65:

In which of the following order the given complex ions are arranged correctly with respect to their decreasing spin only magnetic moment?
(i) [FeF\(_6\)]\(^{3-}\) (ii) [Co(NH\(_3\))\(_6\)]\(^{3+}\) (iii) [NiCl\(_4\)]\(^{2-}\) (iv) [Cu(NH\(_3\))\(_4\)]\(^{2+}\)

  • (1) (i)>(iii)>(iv)>(ii)
  • (2) (ii)>(iii)>(i)>(iv)
  • (3) (iii)>(iv)>(ii)>(i)
  • (4) (ii)>(i)>(iii)>(iv)

Question 66:

The correct order of acid character of the following compounds is : 
I: Phenol, II: p-Nitrobenzoic acid, III: Benzoic acid, IV: p-Toluic acid 

  • (1) I>II>III>IV
  • (2) III>II>I>IV
  • (3) II>III>IV>I
  • (4) IV>III>II>I

Question 67:

The major product of the following reaction is :

  • (1)
  • (2)
  • (3)
  • (4)

Question 68:

Correct statement about the given chemical reaction is : 

  • (1) -NH\(_2\) group is ortho and para directive, so product (B) is not possible.
  • (2) Reaction is possible and compound (B) will be the major product.
  • (3) The reaction will form sulphonated product instead of nitration.
  • (4) Reaction is possible and compound (A) will be the major product.

Question 69:

Given below are two statements:
Statement I: The identification of Ni\(^{2+}\) is carried out by dimethyl glyoxime in the presence of NH\(_4\)OH.
Statement II: The dimethyl glyoxime is a bidentate neutral ligand.

  • (1) Both Statement I and Statement II are true.
  • (2) Both Statement I and Statement II are false.
  • (3) Statement I is true but Statement II is false.
  • (4) Statement I is false but Statement II is true.

Question 70:

Carbylamine test is used to detect the presence of primary amino group in an organic compound. Which of the following compound is formed when this test is performed with aniline ?

  • (1) Phenylmethylamine (NHCH\(_3\))
  • (2) Phenyl cyanide (CN)
  • (3) Phenyl isocyanide (NC)
  • (4) Benzamide (CONH\(_2\))

Question 71:

Which of the following is correct structure of \(\alpha\)-anomer of maltose? 

  • (1) A
  • (2) B
  • (3) C
  • (4) D

Question 72:

Which of the following compound is added to the sodium extract before addition of silver nitrate for testing of halogens?

  • (1) Hydrochloric acid
  • (2) Sodium hydroxide
  • (3) Nitric acid
  • (4) Ammonia

Question 73:

The major product of the following reaction is :

  • (1)
  • (2)
  • (3)
  • (4)

Question 74:

The correct order of bond dissociation enthalpy of halogens is :

  • (1) \(Cl _{2}> F _{2}> Br _{2}> I _{2}\)
  • (2) \(I _{2}> Br _{2}> Cl _{2}> F _{2}\)
  • (3) \(Cl _{2}> Br _{2}> F _{2}> I _{2}\)
  • (4) \(F _{2}> Cl _{2}> Br _{2}> I _{2}\)

Question 75:

The major components of German Silver are :

  • (1) Zn, Ni and Ag
  • (2) Cu, Zn and Ni
  • (3) Cu, Zn and Ag
  • (4) Ge, Cu and Ag

Question 76:

Water does not produce CO on reacting with:

  • (1) C
  • (2) CO\(_2\)
  • (3) C\(_3\)H\(_8\)
  • (4) (Option seems to be missing from OCR)

Question 77:

Given below are two statements:
Statement I: \(\alpha\) and \(\beta\) forms of sulphur can change reversibly between themselves with slow heating or slow cooling.
Statement II: At room temperature the stable crystalline form of sulphur is monoclinic sulphur.

  • (1) Both Statement I and Statement II are true.
  • (2) Both Statement I and Statement II are false.
  • (3) Statement I is true but Statement II is false.
  • (4) Statement I is false but Statement II is true.

Question 78:

The method used for the purification of Indium is:

  • (1) van Arkel method
  • (2) liquation
  • (3) zone refining
  • (4) vapour phase refining

Question 79:

Which one of the following statements is FALSE for hydrophilic sols?

  • (1) They do not require electrolytes for stability.
  • (2) These sols are reversible in nature.
  • (3) Their viscosity is of the order of that of H\(_2\)O.
  • (4) The sols cannot be easily coagulated.

Question 80:

Given below are two statements:
Statement I: The pH of rain water is normally ~5.6.
Statement II: If the pH of rain water drops below 5.6, it is called acid rain.

  • (1) Both Statement I and Statement II are true.
  • (2) Both Statement I and Statement II are false.
  • (3) Statement I is true but Statement II is false.
    %
  • (4) Statement I is false but Statement II is true.

Chemistry - Section B (Q81 - Q90)

Question 81:

Copper reduces NO\(_3^-\) into NO and NO\(_2\) depending upon the concentration of HNO\(_3\) in solution. (Assuming fixed [Cu\(^{2+}\)] and \(P_{NO}=P_{NO_2}\)), the HNO\(_3\) concentration at which the thermodynamic tendency for reduction of NO\(_3^-\) into NO and NO\(_2\) by copper is same is \(10^x\) M. The value of 2x is ________. (Rounded-off to the nearest integer)
[Given, E\(^\circ_{Cu^{2+}/Cu}\)=0.34 V, E\(^\circ_{NO_3^-/NO}\)=0.96 V, E\(^\circ_{NO_3^-/NO_2}\)=0.79 V and at 298 K, \(\frac{RT}{F}\)(2.303)=0.059]


Question 82:

The spin only magnetic moment of a divalent ion in aqueous solution (atomic number 29) is ________ BM.


Question 83:

If a compound AB dissociates to the extent of 75% in an aqueous solution, the molality of the solution which shows a 2.5 K rise in the boiling point of the solution is ________ molal. (Rounded-off to the nearest integer) [K\(_b\)=0.52 K kg mol⁻¹]


Question 84:

Electromagnetic radiation of wavelength 663 nm is just sufficient to ionise the atom of metal A. The ionization energy of metal A in kJ mol⁻¹ is ________ . (Rounded-off to the nearest integer) [h=6.63\(\times\)10⁻³⁴ Js, c=3.00\(\times\)10⁸ ms⁻¹, N\(_A\)=6.02\(\times\)10²³ mol⁻¹]


Question 85:

Consider titration of NaOH solution versus 1.25 M oxalic acid solution. At the end point following burette readings were obtained. (i) 4.5 mL, (ii) 4.5 mL, (iii) 4.4 mL, (iv) 4.4 mL, (v) 4.4 mL. If the volume of oxalic acid taken was 10.0 mL then the molarity of the NaOH solution is _______ M. (Rounded-off to the nearest integer)


Question 86:

Five moles of an ideal gas at 293 K is expanded isothermally from an initial pressure of 2.1 MPa to 1.3 MPa against at constant external pressure 4.3 MPa. The heat transferred in this process is ________ kJ mol⁻¹. (Rounded-off to the nearest integer) [Use R=8.314 J mol⁻¹K⁻¹]


Question 87:

The number of compound/s given below which contain/s —COOH group is ________ . (Integer answer)
(A) Sulphanilic acid (B) Picric acid (C) Aspirin (D) Ascorbic acid


Question 88:

The rate constant of a reaction increases by five times on increase in temperature from 27°C to 52°C. The value of activation energy in kJ mol⁻¹ is ________. (Rounded-off to the nearest integer) [R=8.314 JK⁻¹ mol⁻¹]


Question 89:

Among the following, number of metal/s which can be used as electrodes in the photoelectric cell is ________ . (Integer answer)
(A) Li (B) Na (C) Rb (D) Cs


Question 90:

The unit cell of copper corresponds to a face centered cube of edge length 3.596 Å with one copper atom at each lattice point. The calculated density of copper in kg/m³ is ________ . [Molar mass of Cu: 63.54 g; Avogadro Number=6.022\(\times\)10²³]

JEE Main 2021 Exam Pattern and Marking Scheme

ParticularsDetails
Exam ModeOnline (Computer-Based Test)
PaperB.E./B.Tech (Paper 1)
Duration3 hours (180 minutes)
Type of QuestionsMultiple Choice Questions (MCQs) + Numerical Value Questions
SubjectsMathematics, Physics, Chemistry
Total Questions90 questions (75 to be attempted)
Total Marks300 marks
Marking Scheme+4 for correct answer & -1 for incorrect MCQ; no negative marking for Numerical Value Questions

JEE Main 2021 February 25 Shift 2 Difficulty Level

JEE Main 2021 B.E./B.Tech Question Paper- February 25, 2021- Afternoon Session was rated by the applicants to be of moderate difficulty. Questions from the Class XII syllabus dominated a large part of the paper, with only a few questions based on the class XI syllabus. Few questions were more or less the same as given in NCERT books of the respective subjects.

JEE Main 2021 B.E./B.Tech Question Paper February 25 (Afternoon Session): Paper Analysis

JEE Main 2021 B.E./B.Tech February 25 (Afternoon Session) was conducted between 3.00 PM to 6.00 PM. The difficulty level of the paper was moderate.

  • A total of 51 Questions were asked from the class XII syllabus and 39 Questions were asked from the class XI syllabus. Check JEE Main Syllabus
  • Mathematics section had high weightage assigned to Differential Calculus, Integral Calculus, and Coordinate Geometry. The number of questions from the class XII syllabus was significantly higher in this section.
  • Questions in the section were of moderate difficulty, except for a few lengthy and complex questions from Integral Calculus and Probability.
  • Physics section had a large number of questions from Electrodynamics, Modern Physics, Simple Harmonic Motion, and Waves. Most of the questions were of moderate difficulty, however, few highly complex questions were asked from Electrodynamics.
  • Chemistry section was dominated by questions from Organic Chemistry topics. The number of questions based on the class XII syllabus was significantly higher in this section too.
  • The Questions in the Chemistry section were of easy to moderate difficulty.

For detailed JEE Main Question Paper Analysis, visit: JEE Main Question Paper Analysis