JEE Main 2026 — 24 Jan Shift 1 (9:00 AM - 12:00 PM) (Previous Year
JEE Main · 2026 · with answers and explanations
- questions
- 74
- Total marks
- 296
- Duration
- 180 minutes
- Negative marking
- −1
Subjects: Mathematics · Physics · Chemistry
Question 1
Mathematics · 4 marks · −1Let R be a relation defined on the set by . Then the number of elements in R is
- A.18
- B.12
- C.6
- D.15
Correct answer: B
Question 2
Mathematics · 4 marks · −1If the domain of the function is , then equals:
- A.177
- B.170
- C.307
- D.316
Correct answer: D
Question 3
Mathematics · 4 marks · −1Let . Then is equal to
- A.398
- B.385
- C.423
- D.413
Correct answer: B
Explanation: First condition: Im z = 4. With : , ; .
Question 4
Mathematics · 4 marks · −1Let 729, 81, 9, 1, ... be a sequence and denote the product of the first n terms of this sequence. If and , then is equal to
- A.73
- B.75
- C.76
- D.74
Correct answer: A
Explanation: ; : .
Question 5
Mathematics · 4 marks · −1The number of the real solutions of the equation: is
- A.5
- B.4
- C.2
- D.3
Correct answer: D
Question 6
Mathematics · 4 marks · −1Consider an A.P.: ; . If , , and , then is equal to
- A.136
- B.476
- C.238
- D.952
Correct answer: C
Explanation: and give , , ; .
Question 7
Mathematics · 4 marks · −1Let up to 13 terms. If , , then is equal to
- A.52
- B.51
- C.49
- D.50
Correct answer: C
Explanation: ; : .
Question 8
Mathematics · 4 marks · −1The mean and variance of a data of 10 observations are 10 and 2, respectively. If an observations in this data is replaced by , then the mean and variance become 10.1 and 1.99, respectively. Then equals
- A.10
- B.15
- C.20
- D.5
Correct answer: C
Explanation: ; : , so , .
Question 9
Mathematics · 4 marks · −1From a lot containing 10 defective and 90 non-defective bulbs, 8 bulbs are selected one by one with replacement. Then the probability of getting at least 7 defective bulbs is
- A.
- B.
- C.
- D.
Correct answer: B
Explanation: .
Question 10
Mathematics · 4 marks · −1Let each of the two ellipses , and , have eccentricity . Let the lengths of the latus recta of and be and , respectively, such that . If the distance between the foci of is 8, then the distance between the foci of is
- A.
- B.
- C.
- D.
Correct answer: D
Question 11
Mathematics · 4 marks · −1Let a circle of radius 4 pass through the origin O, the points and , where a and b are real parameters and . Then the locus of the centroid of is a circle of radius
- A.
- B.
- C.
- D.
Correct answer: A
Explanation: AB is a diameter: ; centroid gives , radius .
Question 12
Mathematics · 4 marks · −1If for some , then is equal to
- A.
- B.
- C.
- D.
Correct answer: A
Explanation: Expression ; with , in the second quadrant: , ; sum .
Question 13
Mathematics · 4 marks · −1Let A(1, 0), B(2, $-\left(\frac{7}{3}, \frac{4}{3}\right)$ be three points. If the equation of the bisector of the angle ABC is , then the value of is
- A.10
- B.8
- C.13
- D.5
Correct answer: A
Question 14
Mathematics · 4 marks · −1The value of is equal to
- A.32
- B.64
- C.12
- D.16
Correct answer: B
Explanation: Numerator ; denominator ; value 64.
Question 15
Mathematics · 4 marks · −1Let , and . Let be a vector such that , and the angle between and is . Then is equal to
- A.1
- B.3
- C.11
- D.0
Correct answer: D
Explanation: , so ; .
Question 16
Mathematics · 4 marks · −1Let the lines , and , , intersect at the point R. Let P and Q be the points lying on lines and , respectively, such that and . If the point P lies in the first octant, then is equal to
- A.340
- B.348
- C.360
- D.320
Correct answer: C
Question 17
Mathematics · 4 marks · −1If the function is continuous at , then the value of is equal to
- A.
- B.
- C.2
- D.
Correct answer: B
Explanation: ; ; limit .
Question 18
Mathematics · 4 marks · −1Let be such that the function be differentiable at all . Then is equal to
- A.48
- B.84
- C.24
- D.36
Correct answer: A
Question 19
Mathematics · 4 marks · −1Let , . If and , then equals
- A.
- B.
- C.
- D.
Correct answer: C
Explanation: With : ; from the given value, so .
Question 20
Mathematics · 4 marks · −1Let be the bounded area enclosed by the curves , and -axis that lies in the first quadrant. Let be the bounded area enclosed by the curves , , , and -axis that lies in the first quadrant. Then is equal to
- A.
- B.
- C.
- D.
Correct answer: C
Explanation: ; ; difference .
Question 21
Mathematics · 4 marks · −1The number of matrices A, which can be formed using the elements of the set such that the sum of all the diagonal elements of is 5, is ______
Correct answer: 312
Explanation: Sum of squares of the 6 entries = 5: one and one () or five (): 312.
Question 22
Mathematics · 4 marks · −1The number of numbers greater than 5000, less than 9000 and divisible by 3, that can be formed using the digits 0, 1, 2, 5, 9, if the repetition of the digits is allowed, is ______
Correct answer: 42
Question 23
Mathematics · 4 marks · −1Let a line L passing through the point P(1,1,1) be perpendicular to the lines and . Let the line L intersect the -plane at the point Q. Another line parallel to L and passing through the point S(1, 0, $-$1) intersects the -plane at the point R. Then the square of the area of the parallelogram PQRS is equal to ______.
Correct answer: 6
Explanation: Direction ; Q = (0,2,4); PQ = (-1,1,3), PS = (0,-1,-2); .
Question 24
Mathematics · 4 marks · −1Let be the largest interval in which the function , , is strictly decreasing. Then the local maximum value of the function , , is ______
Correct answer: 4
Explanation: decreases on , so ; , at : .
Question 25
Mathematics · 4 marks · −1Let a differentiable function satisfy the equation . If is a standard parabola passing through the points (2, 1) and ($-$4, ), then is equal to ______.
Correct answer: 64
Explanation: : ; , ; .
Question 26
Physics · 4 marks · −1Match the LIST-I with LIST-II. List-I: A. Magnetic induction; B. Magnetic flux; C. Magnetic permeability; D. Self inductance. List-II: I. ; II. ; III. ; IV. . Choose the correct answer from the options given below:
- A.A-III, B-IV, C-II, D-I
- B.A-I, B-III, C-IV, D-II
- C.A-IV, B-III, C-I, D-II
- D.A-III, B-IV, C-I, D-II
Correct answer: D
Question 27
Physics · 4 marks · −1A spring of force constant 15 N/m is cut into two pieces. If the ratio of their length is 1:3, then the force constant of smaller piece is ______ N/m.
- A.60
- B.45
- C.20
- D.15
Correct answer: A
Explanation: : smaller piece has the length, N/m.
Question 28
Physics · 4 marks · −1Two resistors 2 and 3 are connected in the gaps of bridge as shown in figure. The null point is obtained with the contact of jockey at some point on wire XY. When an unknown resistor is connected in parallel with 3 resistor, the null point is shifted by 22.5 cm toward Y. The resistance of unknown resistor is ______ .

- A.2
- B.3
- C.4
- D.1
Correct answer: A
Explanation: Initially cm; new cm: ; .
Question 29
Physics · 4 marks · −1Three masses 200 kg, 300 kg and 400 kg are placed at the vertices of an equilateral triangle with sides 20 m. They are rearranged on the vertices of a bigger triangle of side 25 m and with the same centre. The work done in this process ______ J. (Gravitational constant N m/kg)
- A.
- B.
- C.
- D.
Correct answer: D
Explanation: ; J.
Question 30
Physics · 4 marks · −1A boy throws a ball into air at from the horizontal to land it on a roof of a building of height H. If the ball attains maximum height in 2 s and lands on the building in 3 s after launch, then value of H is ______ m. ( m/s)
- A.25
- B.10
- C.15
- D.20
Correct answer: C
Explanation: m/s; m.
Question 31
Physics · 4 marks · −1Two masses 400 g and 350 g are suspended from the ends of a light string passing over a heavy pulley of radius 2 cm. When released from rest the heavier mass is observed to fall 81 cm in 9 s. The rotational inertia of the pulley is ______ kg.m. ( m/s)
- A.
- B.
- C.
- D.
Correct answer: A
Explanation: m/s; , kg m.
Question 32
Physics · 4 marks · −1Density of water at C and C are 1000 kg/m and 998 kg/m respectively. The increase in internal energy of 4 kg of water when it is heated from C to C is ______ J. (specific heat capacity of water = 4.2 J/kg. and 1 atmospheric pressure Pa)
- A.315826.2
- B.258700.8
- C.234699.2
- D.268799.2
Correct answer: D
Question 33
Physics · 4 marks · −1A brass wire of length 2 m and radius 1 mm at C is held taut between two rigid supports. Initially it was cooled to a temperature of C creating a tension T in the wire. The temperature to which the wire has to be cooled in order to increase the tension in it to 1.4T, is ______ C.
- A.-71
- B.-65
- C.-80
- D.-86
Correct answer: A
Explanation: : , so C.
Question 34
Physics · 4 marks · −1A cylindrical block of mass M and area of cross section A is floating in a liquid of density and with its axis vertical. When depressed a little and released the block starts oscillating. The period of oscillation is ______.
- A.
- B.
- C.
- D.
Correct answer: C
Question 35
Physics · 4 marks · −1The electrostatic potential in a charged spherical region of radius r varies as , where a and b are constants. The total charge in the sphere of unit radius is . The value of is ______. (permittivity of vacuum is )
- A.-8
- B.-12
- C.-9
- D.-6
Correct answer: B
Explanation: ; Gauss at : .
Question 36
Physics · 4 marks · −1Two resistors of 100 each are connected in series with a 9 V battery. A voltmeter of 400 resistance is connected to measure the voltage drop across one of the resistors. The voltmeter reading is ______ V.
- A.2
- B.3
- C.4
- D.4.5
Correct answer: C
Explanation: ; V.
Question 37
Physics · 4 marks · −1For the series LCR circuit connected with 220 V, 50 Hz a.c source as shown in the figure, the power factor is . The value of is ______.

- A.4
- B.8
- C.10
- D.6
Correct answer: D
Explanation: ; .
Question 38
Physics · 4 marks · −1There are three co-centric conducting spherical shells A, B and C of radii a, b and c respectively and they are charged with charge , and respectively. The potentials of the spheres A, B and C respectively, are :
- A.
- B.
- C.
- D.
Correct answer: C
Question 39
Physics · 4 marks · −1Three charges , and are situated at , and respectively in the plane. The resultant dipole moment about origin is ______.
- A.
- B.
- C.
- D.
Correct answer: A
Explanation: .
Question 40
Physics · 4 marks · −1Match the LIST-I with LIST-II. List-I: A. Radio-wave; B. Micro-wave; C. Infrared-wave; D. X-ray. List-II: I. is produced by Magnetron valve; II. due to change in the vibrational modes of atoms; III. due to inner shell electrons moving from higher energy level to lower energy level; IV. due to rapid acceleration of electrons. Choose the correct answer from the options given below:
- A.A-IV, B-II, C-I, D-III
- B.A-IV, B-III, C-I, D-II
- C.A-IV, B-I, C-II, D-III
- D.A-II, B-IV, C-III, D-I
Correct answer: C
Question 41
Physics · 4 marks · −1An unpolarised light is incident at an interface of two dielectric media having refractive indices of 2 (incident medium) and (medium) respectively. To satisfy the condition that reflected and refracted rays are perpendicular to each other, the angle of incidence is ______.
- A.
- B.
- C.
- D.
Correct answer: D
Explanation: .
Question 42
Physics · 4 marks · −1In a microscope of tube length 10 cm two convex lenses are arranged with focal length of 2 cm and 5 cm. Total magnification obtained with this system for normal adjustment is . The value of k is ______.
- A.4
- B.5
- C.3.5
- D.2
Correct answer: D
Explanation: .
Question 43
Physics · 4 marks · −1The exit surface of a prism with refractive index n is coated with a material having refractive index . When this prism is set for minimum angle of deviation, it exactly meets the condition of critical angle. The prism angle is ______.
- A.
- B.
- C.
- D.
Correct answer: B
Explanation: Critical angle at the exit face; at minimum deviation , so .
Question 44
Physics · 4 marks · −1Given below are two statements: Statement I: For all elements, greater the mass of the nucleus, greater is the binding energy per nucleon. Statement II: For all elements, nuclei with less binding energy per nucleon transforms to nuclei with greater binding energy per nucleon. 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.Both Statement I and Statement II are false
- C.Statement I is false but Statement II is true
- D.Both Statement I and Statement II are true
Correct answer: C
Question 45
Physics · 4 marks · −1Two electrons are moving in orbits of two hydrogen like atoms with speeds m/s and m/s respectively. If the radii of these orbits are nearly same then the possible order of energy states are ______ respectively.
- A.10 and 12
- B.8 and 10
- C.6 and 5
- D.9 and 8
Correct answer: C
Explanation: , ; equal r gives , so : .
Question 46
Physics · 4 marks · −1A voltage regulating circuit consisting of Zener diode, having break-down voltage of 10 V and maximum power dissipation of 0.4 W, is operated at 15 V. The approximate value of protective resistance in this circuit is ______ .
Correct answer: 125
Explanation: A; .
Question 47
Physics · 4 marks · −1In the given figure the blocks A, B and C weigh 4 kg, 6 kg and 8 kg respectively. The co-efficient of sliding friction between any two surfaces is 0.5. The force required to slide the block C with constant speed is ______ N. (Use m/s)

Correct answer: 210
Explanation: A is held at rest by the string; C moves left, B moves right. On C: floor friction N, friction from B N and the string tension T, all opposing F. On B (constant speed): N (friction from C and from A). N.
Question 48
Physics · 4 marks · −1Sixty four rain drops of radius 1 mm each falling down with a terminal velocity of 10 cm/s coalesce to form a bigger drop. The terminal velocity of bigger drop is ______ cm/s.
Correct answer: 160
Explanation: ; : 160 cm/s.
Question 49
Physics · 4 marks · −1A gas of certain mass filled in a closed cylinder at a pressure of 3.23 kPa has temperature C. The gas is now heated to double its temperature. The modified pressure is ______ Pa.
Correct answer: 3730
Explanation: 'Double temperature' taken as C: Pa.
Question 50
Physics · 4 marks · −1A short bar magnet placed with its axis at with an external field of 800 Gauss, experiences a torque of 0.016 N.m. The work done in moving it from most stable to most unstable position is J. The value of is ______.
Correct answer: 64
Explanation: ; J.
Question 51
Chemistry · 4 marks · −1Consider a mixture 'X' which is made by dissolving 0.4 mol of [Co(NH)SO]Br and 0.4 mol of [Co(NH)Br]SO in water to make 4 L of solution. When 2 L of mixture 'X' is allowed to react with excess of AgNO, it forms precipitate 'Y'. The rest 2 L of mixture 'X' reacts with excess BaCl to form precipitate 'Z'. Which of the following statements is CORRECT?
- A.'Y' is BaSO and 'Z' is AgBr.
- B.0.1 mol of 'Y' is formed.
- C.0.2 mol of 'Z' is formed.
- D.0.4 mol of 'Z' is formed.
Correct answer: C
Explanation: Each 2 L half holds 0.2 mol of each isomer: 0.2 mol AgBr (Y) and 0.2 mol BaSO (Z).
Question 52
Chemistry · 4 marks · −1Match the LIST-I with LIST-II. List-I (Isothermal process for ideal gas system): A. Reversible expansion; B. Free expansion; C. Irreversible expansion; D. Irreversible compression. List-II (Work done, ): I. ; II. ; III. ; IV. . Choose the correct answer from the options given below:
- A.A-II, B-I, C-III, D-IV
- B.A-IV, B-I, C-III, D-II
- C.A-I, B-III, C-II, D-IV
- D.A-IV, B-II, C-III, D-I
Correct answer: A
Question 53
Chemistry · 4 marks · −1Given below are statements about some molecules/ions. Identify the CORRECT statements. A. The dipole moment value of NF is higher than that of NH. B. The dipole moment value of BeH is zero. C. The bond order of O and F is same. D. The formal charge on the central oxygen atom of ozone is . E. In NO, all the three atoms satisfy the octet rule, hence it is very stable. Choose the correct answer from the options given below:
- A.A, B, C, D & E
- B.B & C Only
- C.B, C & D Only
- D.A, C & D Only
Correct answer: B
Question 54
Chemistry · 4 marks · −1A solution is prepared by dissolving 0.3 g of a non-volatile non-electrolyte solute 'A' of molar mass 60 g mol and 0.9 g of a non-volatile non-electrolyte solute 'B' of molar mass 180 g mol in 100 mL HO at 27C. Osmotic pressure of the solution will be [Given: R = 0.082 L atm K mol]
- A.1.23 atm
- B.0.82 atm
- C.2.46 atm
- D.1.47 atm
Correct answer: C
Explanation: 0.01 mol in 0.1 L: atm.
Question 55
Chemistry · 4 marks · −1'W' g of a non-volatile electrolyte solid solute of molar mass 'M' g mol when dissolved in 100 mL water, decreases vapour pressure of water from 640 mm Hg to 600 mm Hg. If aqueous solution of the electrolyte boils at 375 K and for water is 0.52 K kg mol, then the mole fraction of the electrolyte solute () in the solution can be expressed as (Given : density of water = 1 g/mL and boiling point of water = 373 K)
- A.
- B.
- C.
- D.
Correct answer: C
Question 56
Chemistry · 4 marks · −1At 27C in presence of a catalyst, activation energy of a reaction is lowered by 10 kJ mol. The logarithm of ratio of is.... (Consider that the frequency factor for both the reactions is same)
- A.0.1741
- B.1.741
- C.3.482
- D.17.41
Correct answer: B
Explanation: .
Question 57
Chemistry · 4 marks · −1A D is an endothermic reaction occurring in three steps (elementary). (i) A B = +ve (ii) B C = ve (iii) C D = ve. Which of the following graphs between potential energy (y-axis) vs reaction coordinate (x-axis) correctly represents the reaction profile of A D?

- A.Profile (1) as described
- B.Profile (2): each step as stated, D ends above A
- C.Profile (3) as described
- D.Profile (4) as described
Correct answer: B
Question 58
Chemistry · 4 marks · −1Given below are two statements: Statement I: K > Mg > Al > B is the correct order in terms of metallic character. Statement II: Atomic radius is always greater than the ionic radius for any element. In the light of the above statements, choose the correct answer from the options given below
- A.Statement I is false but Statement II is true
- B.Statement I is true but Statement II is false
- C.Both Statement I and Statement II are false
- D.Both Statement I and Statement II are true
Correct answer: B
Explanation: Anions are larger than their atoms, so II is false.
Question 59
Chemistry · 4 marks · −1Among the following, the CORRECT combinations are A. IF Tshaped (spd) B. IF Square pyramidal (spd) C. IF Pentagonal bipyramidal (spd) D. ClO Square planar (spd). Choose the correct answer from the options given below:
- A.A, B, C and D
- B.B, C and D Only
- C.A and B Only
- D.A, B and C Only
Correct answer: D
Question 60
Chemistry · 4 marks · −1Given below are two statements: Statement I: The number of paramagnetic species among [CoF], [TiF], VO and [Fe(CN)] is 3. Statement II: K[Fe(CN)] < K[Fe(CN)] < [Fe(HO)]SO.HO < [Fe(HO)]Cl is the correct order in terms of number of unpaired electron(s) present in the complexes. 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.Statement I is true but Statement II is false
- D.Both Statement I and Statement II are true
Correct answer: D
Explanation: Paramagnetic: [CoF], [TiF], [Fe(CN)] (3; VO is d). Unpaired: 0 < 1 < 4 < 5. Both true.
Question 61
Chemistry · 4 marks · −1A student is given one compound among the following compounds that gives positive test with Tollen's reagent. A: 2-methoxytetrahydrofuran (OCH on the carbon next to ring O); B: 3-methoxytetrahydrofuran; C: 2-(hydroxy)tetrahydrofuran drawn with OH on the carbon adjacent to ring O (hemiacetal); D: tetrahydrofuran-3-ol. The compound is :

- A.B
- B.A
- C.C
- D.D
Correct answer: C
Explanation: Only the cyclic hemiacetal (C) opens to an aldehyde.
Question 62
Chemistry · 4 marks · −1Arrange the following carbanions in the decreasing order of stability. I. -BrCHH II. CHH III. -CHOCHH IV. -CHOCHH V. -CHCHH. Choose the correct answer from the options given below:
- A.IV > I > II > V > III
- B.I > IV > II > V > III
- C.I > II > IV > V > III
- D.IV > II > I > III > V
Correct answer: A
Question 63
Chemistry · 4 marks · −1Arrange the following alkenes in decreasing order of stability. I. (CH)C=C(CH) (tetrasubstituted) II. trans-disubstituted alkene (drawn with the two H atoms on opposite sides of C=C) III. (CH)C=CH(CH) (trisubstituted) IV. cis-disubstituted alkene (drawn with the two H atoms on the same side of C=C). Choose the correct answer from the options given below:

- A.III > II > I > IV
- B.I > III > II > IV
- C.III > I > II > IV
- D.I > III > IV > II
Correct answer: B
Explanation: More alkyl substitution is more stable; trans more stable than cis.
Question 64
Chemistry · 4 marks · −1Given below are two statements: Statement I: 'CCl' bond is stronger in CH=CHCl than CHCHCl. Statement II: The given optically active molecule, C(Ph)(Me)(Et)Cl (a chiral tertiary benzylic chloride), on hydrolysis gives a solution that can rotate the plane polarized light. 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 true but Statement II is false
- C.Both Statement I and Statement II are true
- D.Statement I is false but Statement II is true
Correct answer: B
Explanation: Vinylic CCl has partial double-bond character (I true); the tertiary benzylic chloride hydrolyses by S$_N$1 via a planar carbocation giving a racemate (II false).
Question 65
Chemistry · 4 marks · −1Match the LIST-I with LIST-II. List-I (Chloro derivative): A. Vinyl Chloride; B. Benzyl Chloride; C. Alkyl Chloride; D. Allyl Chloride. List-II (Example): I. CH=CHCHCl; II. CHCH(Cl)CH; III. CH=CHCl; IV. CHCH(Cl)CH. Choose the correct answer from the options given below:
- A.A-III, B-IV, C-I, D-II
- B.A-III, B-IV, C-II, D-I
- C.A-I, B-II, C-IV, D-III
- D.A-IV, B-I, C-III, D-II
Correct answer: B
Question 66
Chemistry · 4 marks · −1Consider the following two reactions A and B. (A) Phenol Main Product + gas (x). (B) Benzoic acid Main Product + gas (y). Numerical value of [molar mass of x + molar mass of y] is ______.
- A.46
- B.88
- C.160
- D.4
Correct answer: A
Explanation: H (2) + CO (44) = 46.
Question 67
Chemistry · 4 marks · −1The correct stability order of the following diazonium salts is (A) -CHOCHNCl (B) -NOCHNCl (C) CHNCl (D) -CNCHNCl
- A.A > C > D > B
- B.A > B > C > D
- C.C > D > B > A
- D.C > A > D > B
Correct answer: A
Question 68
Chemistry · 4 marks · −1A hydroxy compound (X) with molar mass 122 g mol is acetylated with acetic anhydride, using a large excess of the reagent ensuring complete acetylation of all hydroxyl groups. The product obtained has a molar mass of 290 g mol. The number of hydroxyl groups present in compound (X) is:
- A.3
- B.5
- C.4
- D.2
Correct answer: C
Explanation: Each acetylation adds 42: .
Question 69
Chemistry · 4 marks · −1Consider three metal chlorides x, y and z, where x is water soluble at room temperature, y is sparingly soluble in water at room temperature and z is soluble in hot water. x, y and z are respectively
- A.AlCl, PbCl and BaCl
- B.AgCl, HgCl and PbCl
- C.CuCl, AgCl and PbCl
- D.MgCl, AgCl and AlCl
Correct answer: C
Question 70
Chemistry · 4 marks · −1X and Y are the number of electrons involved, respectively during the oxidation of I to I and S to S by acidified KCrO. The value of X + Y is ______.
Correct answer: 12
Explanation: Per mole of KCrO (6 e accepted), 6 electrons are released in each oxidation (6I$^-\to_2^{2-}\to$3S): X + Y = 12 (NTA key).
Question 71
Chemistry · 4 marks · −1In Dumas method for estimation of nitrogen, 0.50 g of an organic compound gave 70 mL of nitrogen collected at 300 K and 715 mm pressure. The percentage of nitrogen in the organic compound is ______ %. (Aqueous tension at 300 K is 15 mm).
Correct answer: 15
Explanation: Dry N at STP mL; mass g; 14.7% 15.
Question 72
Chemistry · 4 marks · −1The hydrogen spectrum consists of several spectral lines in Lyman series (L, L, L...; L has lowest energy among Lyman series). Similarly it consists of several spectral lines in Balmer series (B, B, B ...; B has lowest energy among Balmer lines). The energy of L is x times the energy of B. The value of x is ______ . (Nearest integer)
Correct answer: 54
Explanation: .
Question 73
Chemistry · 4 marks · −1Consider two Group IV metal ions X and Y. A solution containing 0.01 M X and 0.01 M Y is saturated with HS. The pH at which the metal sulphide YS will form as a precipitate is ______. (Nearest integer) (Given: (XS) at 25C, (YS) at 25C, [HS] = 0.1M in solution, (HS) , log 2 = 0.30, log 3 = 0.48, log 5 = 0.70)
Correct answer: 4
Explanation: [S] needed ; [H], [H] , pH .
Question 74
Chemistry · 4 marks · −1Electricity is passed through an acidic solution of Cu till all the Cu was exhausted, leading to the deposition of 300 mg of Cu metal. However, a current of 600 mA was continued to pass through the same solution for another 28 minutes by keeping the total volume of the solution fixed at 200 mL. The total volume of oxygen evolved at STP during the entire process is ______ mL. (Nearest integer) [Given: Cu(aq) + 2e Cu(s) = +0.34 V; O(g) + 4H + 4e 2HO = +1.23 V; Molar mass of Cu = 63.54 g mol; Molar mass of O = 32 g mol; Faraday Constant = 96500 C mol; Molar volume at STP = 22.4 L]
Correct answer: 111
Explanation: Stage 1: F gives 52.9 mL O. Stage 2: C F gives 58.5 mL O (plus H at cathode). Total mL.