JEE Main 2025 — 24 Jan Shift 2 (Previous Year Paper)
JEE Main · 2025 · with answers and explanations
- questions
- 75
- Total marks
- 300
- Duration
- 180 minutes
- Negative marking
- −1
Subjects: Mathematics · Physics · Chemistry
Question 1
Mathematics · 4 marks · −1If , then the value of is :
- A.1
- B.6
- C.
- D.
Correct answer: B
Explanation: ⇒ ⇒ α = 6.
Question 2
Mathematics · 4 marks · −1The number of real solution(s) of the equation is :
- A.0
- B.3
- C.2
- D.1
Correct answer: C
Question 3
Mathematics · 4 marks · −1Let (2, 3) be the largest open interval in which the function is strictly increasing and (b, c) be the largest open interval, in which the function is strictly decreasing. Then is equal to :
- A.280
- B.360
- C.420
- D.160
Correct answer: B
Explanation: : ⇒ a = 5. , : decreasing on (11/5, 3). .
Question 4
Mathematics · 4 marks · −1Let , and . Then the projection of on is :
- A.
- B.
- C.
- D.
Correct answer: D
Explanation: , ; ; projection .
Question 5
Mathematics · 4 marks · −1Let the position vectors of three vertices of a triangle be , and . If the position vectors of the orthocenter and the circumcenter of the triangle are and respectively, then is equal to :
- A.6
- B.3
- C.4
- D.1
Correct answer: B
Explanation: Centroid ; : .
Question 6
Mathematics · 4 marks · −1Suppose A and B are the coefficients of and terms respectively in the binomial expansion of . If 2A = 5B, then n is equal to :
- A.20
- B.19
- C.22
- D.21
Correct answer: D
Question 7
Mathematics · 4 marks · −1If the equation of the parabola with vertex and the directrix is , then is equal to :
- A.7
- B.8
- C.9
- D.6
Correct answer: C
Explanation: Focus (3, 6); ⇒ : 4 + 1 + 4 = 9.
Question 8
Mathematics · 4 marks · −1If the system of equations , , has infinitely many solutions, then is equal to :
- A.13
- B.10
- C.12
- D.11
Correct answer: C
Question 9
Mathematics · 4 marks · −1The function , defined by is :
- A.Both one-one and onto
- B.Neither one-one nor onto
- C.One-one but not onto
- D.Onto but not one-one
Correct answer: C
Explanation: f is strictly increasing with range (−1, 1) ≠ codomain.
Question 10
Mathematics · 4 marks · −1The equation of the chord, of the ellipse , whose mid-point is (3, 1) is :
- A.
- B.
- C.
- D.
Correct answer: C
Explanation: : ⇒ .
Question 11
Mathematics · 4 marks · −1Let be a function which is differentiable at all points of its domain and satisfies the condition , with . Then 2f(2) is equal to :
- A.29
- B.19
- C.39
- D.23
Correct answer: C
Explanation: ⇒ ; .
Question 12
Mathematics · 4 marks · −1Let be a square matrix of order 2 with entries either 0 or 1. Let E be the event that A is an invertible matrix. Then the probability P(E) is :
- A.
- B.
- C.
- D.
Correct answer: B
Explanation: 6 of the 16 matrices have ad − bc ≠ 0: 3/8.
Question 13
Mathematics · 4 marks · −1Group A consists of 7 boys and 3 girls, while group B consists of 6 boys and 5 girls. The number of ways, 4 boys and 4 girls can be invited for a picnic if 5 of them must be from group A and the remaining 3 from group B, is equal to :
- A.9100
- B.8575
- C.8750
- D.8925
Correct answer: D
Question 14
Mathematics · 4 marks · −1Let the points lie on or inside the triangle with sides , and . Then the product of the smallest and the largest values of is equal to :
- A.33
- B.55
- C.22
- D.44
Correct answer: A
Explanation: Vertices (6, 5), (4, 7), (10, 3). On x = 11/2 the triangle lies between x + y = 11 (y = 5.5) and 2x + 3y = 29 (y = 6): product 33.
Question 15
Mathematics · 4 marks · −1In an arithmetic progression, if and , then is equal to :
- A.505
- B.525
- C.510
- D.515
Correct answer: D
Explanation: , ⇒ d = 1.5, a = −24.5; .
Question 16
Mathematics · 4 marks · −1The area of the region enclosed by the curves , and y-axis is :
- A.
- B.
- C.
- D.
Correct answer: D
Explanation: The bounded region lies in x ≤ 0 between (above) and (below) from (where they meet) to x = 0: .
Question 17
Mathematics · 4 marks · −1Let and . Then is equal to :
- A.4
- B.8
- C.2
- D.6
Correct answer: B
Question 18
Mathematics · 4 marks · −1Let [x] denote the greatest integer function, and let m and n respectively be the numbers of the points, where the function , , is not continuous and not differentiable. Then m + n is equal to :
- A.8
- B.9
- C.6
- D.7
Correct answer: A
Explanation: Discontinuous at −1, 0, 1, 2 (m = 4); non-differentiable at those 4 points (x = 2 also a kink) (n = 4): 8.
Question 19
Mathematics · 4 marks · −1For some a, b, let , , . Then is equal to :
- A.25
- B.36
- C.9
- D.16
Correct answer: D
Explanation: With : , so λ = 2, μ = ν = 1: .
Question 20
Mathematics · 4 marks · −1If , then the expression is equal to :
- A.0
- B.
- C.
- D.
Correct answer: D
Question 21
Mathematics · 4 marks · −1Let be the solution of the differential equation , . If , then is equal to ______.
Correct answer: 1
Question 22
Mathematics · 4 marks · −1If , where C is the constant of integration, then is equal to ______.
Correct answer: 16
Question 23
Mathematics · 4 marks · −1Number of functions , that assign 1 to exactly one of the positive integers less than or equal to 98, is equal to ______.
Correct answer: 392
Explanation: Choose the one among 1..98 (98 ways); 99 and 100 free (4 ways): 392.
Question 24
Mathematics · 4 marks · −1Let and be two hyperbolas having length of latus rectums and respectively. Let their ecentricities be and respectively. If the product of the lengths of their transverse axes is , then is equal to ______.
Correct answer: 55
Question 25
Mathematics · 4 marks · −1Let P be the image of the point Q(7, −2, 5) in the line L: and R(5, p, q) be a point on L. Then the square of the area of is ______.
Correct answer: 957
Question 26
Physics · 4 marks · −1Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : A electron in a certain region of uniform magnetic field is moving with constant velocity in a straight line path. Reason (R) : The magnetic field in that region is along the direction of velocity of the electron. In the light of the above statements, choose the correct answer from the options given below :
- A.Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
- B.(A) is true but (R) is false
- C.Both (A) and (R) are true and (R) is the correct explanation of (A)
- D.(A) is false but (R) is true
Correct answer: C
Question 27
Physics · 4 marks · −1The magnitude of heat exchanged by a system for the given cyclic process ABCA (as shown in figure) is (in SI unit) :

- A.zero
- B.
- C.
- D.
Correct answer: C
Explanation: Area of the semicircle J.
Question 28
Physics · 4 marks · −1The output of the circuit is low (zero) for : [X and Y feed an OR gate whose output feeds both inputs of a NAND gate] (A) X=0, Y=0 (B) X=0, Y=1 (C) X=1, Y=0 (D) X=1, Y=1. Choose the correct answer from the options given below :

- A.(A), (B) and (C) only
- B.(B), (C) and (D) only
- C.(A), (B) and (D) only
- D.(A), (C) and (D) only
Correct answer: B
Explanation: Output = NOR(X, Y): low whenever any input is 1.
Question 29
Physics · 4 marks · −1A small uncharged conducting sphere is placed in contact with an identical sphere but having C charge and then removed to a distance such that the force of repulsion between them is N. The distance between them is (Take as in SI units)
- A.4 cm
- B.2 cm
- C.3 cm
- D.1 cm
Correct answer: B
Explanation: ⇒ r = 2 cm.
Question 30
Physics · 4 marks · −1In a Young's double slit experiment, three polarizers are kept as shown in the figure. The transmission axes of and are orthogonal to each other. The polarizer covers both the slits with its transmission axis at 45° to those of and . An unpolarized light of wavelength and intensity is incident on and . The intensity at a point after where the path difference between the light waves from and is , is

- A.
- B.
- C.
- D.
Correct answer: B
Explanation: Each beam: after /, after , now parallel. Phase : .
Question 31
Physics · 4 marks · −1The temperature of a body in air falls from 40°C to 24°C in 4 minutes. The temperature of the air is 16°C. The temperature of the body in the next 4 minutes will be :
- A. °C
- B. °C
- C. °C
- D. °C
Correct answer: A
Explanation: Average form: ⇒ ; ⇒ .
Question 32
Physics · 4 marks · −1Which of the following figure represents the relation between Celsius and Fahrenheit temperatures ?

- A.Straight line with positive slope, C-intercept negative (crosses the F-axis at a positive F)
- B.Straight line with negative slope through the origin
- C.Straight line with negative slope, positive C-intercept
- D.Straight line with positive slope through the origin
Correct answer: A
Explanation: : positive slope, C = 0 at F = 32 (C-intercept −160/9).
Question 33
Physics · 4 marks · −1In the first configuration (1) as shown in the figure, four identical charges () are kept at the corners A, B, C and D of square of side length 'a'. In the second configuration (2), the same charges are shifted to mid points G, E, H and F, of the square. If , the difference between the potential energies of configuration (2) and (1) is given by :

- A.
- B.
- C.
- D.
Correct answer: B
Explanation: ; midpoints form a square of side : ; difference .
Question 34
Physics · 4 marks · −1Arrange the following in the ascending order of wavelength () : (A) Microwaves () (B) Ultraviolet rays () (C) Infrared rays () (D) X-rays (). Choose the most appropriate answer from the options given below :
- A.
- B.
- C.
- D.
Correct answer: A
Question 35
Physics · 4 marks · −1A long straight wire of a circular cross-section with radius 'a' carries a steady current I. The current I is uniformly distributed across this cross-section. The plot of magnitude of magnetic field B with distance r from the centre of the wire is given by

- A.B decreases exponentially from at r = 0 (to at r = a)
- B.B = 0 inside, jumps at r = a and then decreases as 1/r
- C.B increases linearly from 0 to r = a and then decreases as 1/r
- D.B constant inside and then decreases as 1/r
Correct answer: C
Question 36
Physics · 4 marks · −1The energy E and momentum p of a moving body of mass m are related by some equation. Given that c represents the speed of light, identify the correct equation
- A.
- B.
- C.
- D.
Correct answer: C
Question 37
Physics · 4 marks · −1A solid sphere and a hollow sphere of the same mass and of same radius are rolled on an inclined plane. Let the time taken to reach the bottom by the solid sphere and the hollow sphere be and , respectively, then
- A.
- B.
- C.
- D.
Correct answer: B
Question 38
Physics · 4 marks · −1Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : In an insulated container, a gas is adiabatically shrunk to half of its initial volume. The temperature of the gas decreases. Reason (R) : Free expansion of an ideal gas is an irreversible and an adiabatic process. In the light of the above statements, choose the correct answer from the options given below :
- A.(A) is false but (R) is true
- B.Both (A) and (R) are true and (R) is the correct explanation of (A)
- C.Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
- D.(A) is true but (R) is false
Correct answer: A
Question 39
Physics · 4 marks · −1In photoelectric effect, the stopping potential () v/s frequency () curve is plotted. (h is the Planck's constant and is work function of metal) (A) v/s is linear. (B) The slope of v/s curve (C) h constant is related to the slope of v/s line. (D) The value of electric charge of electron is not required to determine h using the v/s curve. (E) The work function can be estimated without knowing the value of h. Choose the correct answer from the options given below :
- A.(A), (B) and (C) only
- B.(D) and (E) only
- C.(C) and (D) only
- D.(A), (C) and (E) only
Correct answer: D
Explanation: : linear, slope h/e; (−intercept) needs no h.
Question 40
Physics · 4 marks · −1A solid sphere is rolling without slipping on a horizontal plane. The ratio of the linear kinetic energy of the centre of mass of the sphere and rotational kinetic energy is :
- A.
- B.
- C.
- D.
Correct answer: D
Explanation: .
Question 41
Physics · 4 marks · −1Young's double slit inteference apparatus is immersed in a liquid of refractive index 1.44. It has slit separation of 1.5 mm. The slits are illuminated by a parallel beam of light whose wavelength in air is 690 nm. The fringe-width on a screen placed behind the plane of slits at a distance of 0.72 m, will be :
- A.0.63 mm
- B.0.33 mm
- C.0.46 mm
- D.0.23 mm
Correct answer: D
Explanation: mm.
Question 42
Physics · 4 marks · −1A photograph of a landscape is captured by a drone camera at a height of 18 km. The size of the camera film is 2 cm × 2 cm and the area of the landscape photographed is 400 . The focal length of the lens in the drone camera is :
- A.2.5 cm
- B.0.9 cm
- C.1.8 cm
- D.2.8 cm
Correct answer: C
Explanation: Linear magnification ; cm.
Question 43
Physics · 4 marks · −1The position vector of a moving body at any instant of time is given as m. The magnitude and direction of velocity at t = 2s is,
- A. m/s, making an angle of with −ve Y axis
- B. m/s, making an angle of with +ve X axis
- C. m/s, making an angle of with +ve X axis
- D. m/s, making an angle of with −ve Y axis
Correct answer: D
Explanation: : , from the −y axis.
Question 44
Physics · 4 marks · −1A particle oscillates along the x-axis according to the law, where = 1 m. The kinetic energy (K) of the particle as a function of x is correctly represented by the graph

- A.K is maximum at x = 0 and x = 1 and zero at x = 1/2 (U-shaped parabola)
- B.K is zero at x = 0 and x = 1 and maximum at x = 1/2 (inverted parabola)
- C.K flat near x = 0 and 1, dropping to a cusp at zero at x = 1/2
- D.K zero at x = 0 and 1 with a cusp maximum at x = 1/2
Correct answer: B
Explanation: : SHM about x = 1/2 with amplitude 1/2, so — an inverted parabola.
Question 45
Physics · 4 marks · −1N equally spaced charges each of value q, are placed on a circle of radius R. The circle rotates about its axis with an angular velocity as shown in the figure. A bigger Amperian loop B encloses the whole circle where as a smaller Amperian loop A encloses a small segment. The difference between enclosed currents, , for the given Amperian loops is

- A.
- B.
- C.
- D.
Correct answer: A
Explanation: Loop A: current through a section of the ring ; loop B: net 0.
Question 46
Physics · 4 marks · −1Acceleration due to gravity on the surface of earth is 'g'. If the diameter of earth is reduced to one third of its original value and mass remains unchanged, then the acceleration due to gravity on the surface of the earth is ______ g.
Correct answer: 9
Explanation: g ∝ 1/R²: 9g.
Question 47
Physics · 4 marks · −1The increase in pressure required to decrease the volume of a water sample by 0.2% is . Bulk modulus of water is . The value of P is ______.
Correct answer: 43
Explanation: .
Question 48
Physics · 4 marks · −1The ratio of the power of a light source to that the light source is 2. is emitting photons per second at 600 nm. If the wavelength of the source is 300 nm, then the number of photons per second emitted by is ______ .
Correct answer: 5
Explanation: : .
Question 49
Physics · 4 marks · −1A string of length L is fixed at one end and carries a mass of M at the other end. The mass makes rotations per second about the vertical axis passing through end of the string as shown. The tension in the string is ______ ML.

Correct answer: 36
Explanation: with : 36 ML.
Question 50
Physics · 4 marks · −1A tightly wound long solenoid carries a current of 1.5 A. An electron is executing uniform circular motion inside the solenoid with a time period of 75 ns. The number of turns per metre in the solenoid is ______. [Take mass of electron kg, charge of electron C, , 1 ns = s]
Correct answer: 250
Explanation: ⇒ .
Question 51
Chemistry · 4 marks · −1When Ethane-1,2-diamine is added progressively to an aqueous solution of Nickel (II) chloride, the sequence of colour change observed will be :
- A.Green → Pale Blue → Blue → Violet
- B.Violet → Blue → Pale Blue → Green
- C.Pale Blue → Blue → Green → Violet
- D.Pale Blue → Blue → Violet → Green
Correct answer: A
Question 52
Chemistry · 4 marks · −1Given below are two statements : Statement (I) : [graph of vs is a horizontal line] is valid for first order reaction. Statement (II) : [graph of vs time is a straight line through the origin with positive slope = ] is valid for first order reaction. In the light of the above statements, choose the correct answer from the options given below :

- A.Both Statement I and Statement II are false
- B.Statement I is false but Statement II is true
- C.Both Statement I and Statement II are true
- D.Statement I is true but Statement II is false
Correct answer: D
Explanation: has negative slope, so II is false.
Question 53
Chemistry · 4 marks · −1Match List - I with List - II. List - I: (A) Adenine (B) Cytosine (C) Thymine (D) Uracil. List - II: (I) pyrimidine-2,4-dione (uracil skeleton, no methyl) (II) 5-methylpyrimidine-2,4-dione (III) 6-aminopurine (IV) 4-aminopyrimidin-2-one. Choose the correct answer from the options given below :

- A.(A)-(III), (B)-(IV), (C)-(II), (D)-(I)
- B.(A)-(III), (B)-(I), (C)-(IV), (D)-(II)
- C.(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
- D.(A)-(IV), (B)-(III), (C)-(II), (D)-(I)
Correct answer: A
Question 54
Chemistry · 4 marks · −1Given below are two statements : Statement (I) : The first ionization energy of Pb is greater than that of Sn. Statement (II) : The first ionization energy of Ge is greater than that of Si. In the light of the above statements, choose the correct answer from the options given below :
- A.Statement I is true but Statement II is false
- B.Statement I is false but Statement II is true
- C.Both Statement I and Statement II are false
- D.Both Statement I and Statement II are true
Correct answer: A
Explanation: IE₁: Pb 715 > Sn 708 kJ/mol; Ge 762 < Si 786.
Question 55
Chemistry · 4 marks · −1For the reaction, . Attainment of equilibrium is predicted correctly by :

- A. and curves fall from high values and level off ( above ); HI rises from 0 and levels off below both
- B.All three (, , HI) rise from 0 and level off
- C. rises and levels off at top; and HI fall and level off
- D. rises and levels off at top; falls; HI rises and levels off below
Correct answer: A
Question 56
Chemistry · 4 marks · −1In the given structure, number of sp and hybridized carbon atoms present respectively are :

- A.4 and 6
- B.4 and 5
- C.3 and 6
- D.3 and 5
Correct answer: D
Explanation: sp: two alkyne C + nitrile C = 3; sp²: C=O carbon + 4 alkene C = 5.
Question 57
Chemistry · 4 marks · −1Given below are two statements : Statement (I) : Experimentally determined oxygen-oxygen bond lengths in the are found to be same and the bond length is greater than that of a O=O (double bond) but less than that of a single (O−O) bond. Statement (II) : The strong lone pair-lone pair repulsion between oxygen atoms is solely responsible for the fact that the bond length in ozone is smaller than that of a double bond (O=O) but more than that of a single bond (O−O). In the light of the above statements, choose the correct answer from the options given below :
- A.Both Statement I and Statement II are true
- B.Statement I is true but Statement II is false
- C.Both Statement I and Statement II are false
- D.Statement I is false but Statement II is true
Correct answer: B
Question 58
Chemistry · 4 marks · −1For hydrogen atom, the orbital/s with lowest energy is/are : (A) 4s (B) (C) (D) (E) . Choose the correct answer from the options given below :
- A.(A) only
- B.(B) only
- C.(A) and (E) only
- D.(B), (C) and (D) only
Correct answer: D
Question 59
Chemistry · 4 marks · −1kcal; kcal. The heat of formation of is given by :
- A.y − 2x kcal
- B. kcal
- C.x + y kcal
- D.2x + y kcal
Correct answer: A
Explanation: .
Question 60
Chemistry · 4 marks · −1The conditions and consequence that favours the configuration in a metal complex are :
- A.strong field ligand, high spin complex
- B.strong field ligand, low spin complex
- C.weak field ligand, low spin complex
- D.weak field ligand, high spin complex
Correct answer: D
Question 61
Chemistry · 4 marks · −1Match List - I with List - II. List - I: (A) (B) Benzoyl chloride benzaldehyde (C) Toluene benzaldehyde (D) Benzene benzaldehyde. List - II: (I) Etard reaction (II) Gatterman-Koch reaction (III) Rosenmund reduction (IV) Stephen reaction. Choose the correct answer from the options given below :
- A.(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
- B.(A)-(I), (B)-(III), (C)-(II), (D)-(IV)
- C.(A)-(III), (B)-(IV), (C)-(II), (D)-(I)
- D.(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
Correct answer: D
Question 62
Chemistry · 4 marks · −1The structure of the major product formed in the following reaction is : 3-bromo-5-iodobenzyl chloride major product

- A.1-bromo-3-(chloromethyl)-5-cyanobenzene (CN replaces ring I)
- B.3-bromo-5-iodobenzyl cyanide ()
- C.3-bromo-5-iodobenzyl isocyanide ()
- D.3-iodo-5-cyanobenzyl chloride (CN replaces ring Br)
Correct answer: C
Explanation: AgCN (covalent) attacks through N at the benzylic carbon: isocyanide; aryl halides are unreactive.
Question 63
Chemistry · 4 marks · −1Based on the data given below : V, V, V, V, the strongest reducing agent is :
- A.
- B.
- C.
- D.Cr
Correct answer: D
Question 64
Chemistry · 4 marks · −1The successive 5 ionisation energies of an element are 800, 2427, 3658, 25024 and 32824 kJ/mol, respectively. By using the above values predict the group in which the above element is present :
- A.Group 13
- B.Group 4
- C.Group 2
- D.Group 14
Correct answer: A
Explanation: Big jump after the 3rd IE: 3 valence electrons (boron).
Question 65
Chemistry · 4 marks · −1For reaction Aniline 2-Bromoaniline (Major). The correct order of set of reagents for the above conversion is :
- A., , , NaOH
- B., , , , NaOH
- C., , , NaOH
- D., , NaOH
Correct answer: B
Explanation: Sulphonate to block the para position (sulphanilic acid), acetylate the amino group to moderate it, brominate ortho, then hot aqueous hydrolysis removes the and acetyl groups; NaOH liberates 2-bromoaniline.
Question 66
Chemistry · 4 marks · −1Find the compound 'A' from the following reaction sequences. A B yellow ppt
- A.NiS
- B.ZnS
- C.MnS
- D.CoS
Correct answer: D
Explanation: Yellow confirms cobalt.
Question 67
Chemistry · 4 marks · −1The elemental composition of a compound is 54.2% C, 9.2% H and 36.6% O. If the molar mass of the compound is 132 g , the molecular formula of the compound is : [Given : The relative atomic mass of C : H : O = 12 : 1 : 16]
- A.
- B.
- C.
- D.
Correct answer: D
Explanation: Empirical (44) × 3 = 132.
Question 68
Chemistry · 4 marks · −1Which of the following mixing of 1M base and 1M acid leads to the largest increase in temperature ?
- A.30 mL and 30 mL NaOH
- B.45 mL and 25 mL NaOH
- C.30 mL HCl and 30 mL NaOH
- D.50 mL HCl and 20 mL NaOH
Correct answer: C
Explanation: Strong acid–strong base, 30 mmol neutralised in 60 mL gives the largest heat per unit volume.
Question 69
Chemistry · 4 marks · −1Match List - I with List - II. List - I (Transition metal ion): (A) (B) (C) (D) . List - II (Spin only magnetic moment (B.M.)): (I) 3.87 (II) 0.00 (III) 1.73 (IV) 2.84. Choose the correct answer from the options given below :
- A.(A)-(III), (B)-(I), (C)-(IV), (D)-(II)
- B.(A)-(IV), (B)-(II), (C)-(III), (D)-(I)
- C.(A)-(II), (B)-(IV), (C)-(I), (D)-(III)
- D.(A)-(III), (B)-(I), (C)-(II), (D)-(IV)
Correct answer: A
Question 70
Chemistry · 4 marks · −1Identify correct statement/s : (A) and are activating group. (B) −CN and −OH are meta directing group. (C) −CN and are meta directing group. (D) Activating groups act as ortho - and para directing groups. (E) Halides are activating groups. Choose the correct answer from the options given below :
- A.(A) only
- B.(A), (C) and (D) only
- C.(A), (B) and (E) only
- D.(A) and (C) only
Correct answer: B
Question 71
Chemistry · 4 marks · −1Consider a complex reaction taking place in three steps with rate constants , and respectively. The overall rate constant k is given by the expression . If the activation energies of the three steps are 60, 30 and 10 kJ respectively, then the overall energy of activation in kJ is ______. (Nearest integer)
Correct answer: 20
Explanation: .
Question 72
Chemistry · 4 marks · −1The possible number of stereoisomers for 5-phenylpent-4-en-2-ol is ______.
Correct answer: 4
Explanation: One stereocentre (C-2) and a stereogenic C=C: 4.
Question 73
Chemistry · 4 marks · −1In Carius method of estimation of halogen, 0.25 g of an organic compound gave 0.15 g of silver bromide (AgBr). The percentage of Bromine in the organic compound is ______ % (Nearest integer). (Given : Molar mass of Ag is 108 and Br is 80 g )
Correct answer: 255
Explanation: Br = 0.15 × 80/188 = 0.0638 g → 25.5% = 255 × 10⁻¹.
Question 74
Chemistry · 4 marks · −1The hydrocarbon (X) with molar mass 80 g and 90% carbon has ______ degree of unsaturation.
Correct answer: 3
Explanation: C = 72 g (6 C), H = 8: , DU = 3.
Question 75
Chemistry · 4 marks · −1The observed and normal molar masses of compound are 65.6 and 164 respectively. The percent degree of ionisation of is ______%. (Nearest integer)
Correct answer: 75
Explanation: ⇒ α = 75%.