Practice Questions

Q49.The correct sequential addition of reagents in the preparation of 3−nitrobenzoic acid from benzene is: JEE Main 2021 (26 Aug Shift 1) JEE Main Previous Year Paper (1) Br2 / AlBr3, HNO3 /H2 SO4, Mg / ether, CO2, H3O+ (2) Br2 / AlBr3, NaCN, H3O+, HNO3 /H2 SO4 (3) Br2 / AlBr3, HNO3 /H2 SO4, NaCN, H3O+ (4) HNO3 /H2 SO4, Br2 / AlBr3, Mg / ether, CO2, H3O+

Q53.When light of wavelength 248 nm falls on a metal of threshold energy 3. 0 eV , the de-Broglie wavelength of o emitted electrons is ________ A . (Round off to the Nearest Integer). [Use : √3 = 1. 73, h = 6. 63 × 10−34 Js; me = 9. 1 × 10−31 kg; c = 3. 0 × 108 ms−1; 1 eV = 1. 6 × 10−19 J]

Q54.The number of moles of NH3, that must be added to 2 L of 0. 80 MAgNO3 in order to reduce the concentration of Ag+ ions to 5. 0 × 10−8M(Kformation for [Ag (NH3)2]+ = 1. 0 × 108) is __________. (Nearest integer) [Assume no volume change on adding NH3 ]

Q54.The OH− concentration in a mixture of 5. 0 mL of 0. 0504 M NH4 Cl and 2 mL of 0. 0210 M NH3 solution is x × 10−6 M . The value of x is (Nearest integer) [Given Kw = 1 × 10−14 and Kb = 1. 8 × 10−5]

Q55.For the reaction A + B ⇌2C the value of equilibrium constant is 100 at 298 K. If the initial concentration of all the three species is 1 M each, then the equilibrium concentration of C is x × 10-1 M. The value of x is _______. (Nearest integer)

Q55.In basic medium CrO2−4 oxidises S2O2−3 to form SO4 2− and itself changes into Cr (OH)−4 .The volume of 0. 154 MCrO2−4 required to react with 40 mL of 0. 25 MS2 O3 2− is _____ mL. (Rounded-off to the nearest integer)

Q56.A solute A dimerizes in water. The boiling point of a 2 molal solution of A is 100. 52∘C. The percentage association of A is ___ . (Round off to the Nearest integer) Use : Kb for water = 0. 52 K kg mol−1 Boiling point of water = 100°C

Q56.Consider the following cell reaction Cd(s) + Hg2 SO4( s) + 95 H2O(l) ⇌CdSO4 ⋅95 H2O(s) + 2 Hg(l). The value of E0cell is 4. 315 V at 25°C. If ΔH°= −825. 2 kJ mol−1, the standard entropy change ΔS° in J K−1 is _________ . (Nearest integer) [Given : Faraday constant = 96487 C mol−1 ]

Q56.A 1 molal K4 Fe(CN)6 solution has a degree of dissociation of 0. 4 . Its boiling point is equal to that of another solution which contains 18. 1 weight percent of a non electrolytic solute A . The molar mass of A is _____ u. (Round off to the Nearest Integer). [Density of water = 1. 0 g cm−3]

Q56. Ga (atomic mass 70 u ) crystallizes in a hexagonal close packed structure. The total number of voids in 0. 581 g of Ga is ________ ×1021 . (Round off to the Nearest Integer).

Q57.Consider the following reaction MnO−4 + 8H+ + 5e−→Mn+2 + 4H2O , E°= 1. 51 V The quantity of electricity required in Faraday to reduce five moles of MnO−4 is

Q57.Copper reduces NO−3 into NO and NO2 depending upon the concentration of HNO3 in solution. (Assuming fixed [Cu2+] and PNO = PNO2 ), the HNO3 concentration at which the thermodynamic tendency for reduction of NO−3 into NO and NO2 by copper is same is 10x M. The value of 2x is ___. (Rounded-off to the nearest integer) [Given, Eo = 0. 34 V, Eo = 0. 96 V, Eo = 0. 79 V and at 298 K, RTF (2. 303) = 0. 059] Cu2+ / Cu NO−3 / NO NO−3 / NO2

Q58.Sucrose hydrolyses in acid solution into glucose and fructose following first order rate law with a half-life of 3. 33 h at 25°C. After 9 h, the fraction of sucrose remaining is f. The value of log10( 1f ) is ________ ×10−2. (Rounded off to the nearest integer) [Assume: In 10 = 2. 303, ln 2 = 0. 693]

Q58.For the cell Cu(s) Cu2+(aq)(0. 1M)∥Ag+(aq)(0. 01M) Ag(s) the cell potential E1 = 0. 3095 V . For the cell Cu(s) Cu2+(aq)(0. 01M)∥Ag+(aq)(0. 001M) Ag(s) the cell potential = x × 10−2 V. Find value of x (Round off the Nearest Integer). [ Use : 2.303F RT = 0. 059 J ]

Q59.A xenon compound A upon partial hydrolysis gives XeO2 F2 . The number of lone pair of electrons present in compound A is ___ (Round off to the Nearest integer)

Q59.Consider the cell at 25°C ZnZn2 + aq, 1 M‖Fe3 + (aq), Fe2 + aqPts The fraction of total iron present as Fe3 + ion at the cell potential of 1 . 500 V is x × 10-2. The value of x is ______. (Nearest integer) Given: E∘ + + = 0 . 77V, E∘ + = - 0 . 76V Fe3 | Fe2 Zn2 | Zn

Q59. A and B decompose via first order kinetics with half-lives 54. 0 min and 18. 0 min respectively. Starting from an equimolar non-reactive mixture of A and B, the time taken for the concentration of A to become 16 times that of B is ______ min. (Round off to the Nearest Integer). Q60. [Ti (H2O)6]3+ absorbs light of wavelength 498 nm during a d −d transition. The octahedral splitting energy for the above complex is _______ ×10−19 J. (Round off to the Nearest Integer). h = 6. 626 × 10−34 Js; c = 3 × 108 ms−1 .

Q60.In the electrolytic refining of blister copper, the total number of main impurities, from the following, removed as anode mud is ___________ . Pb, Sb, Se, Te, Ru, Ag, Au and Pt

Q60.The total number of negative charge in the tetrapeptide, Gly-Glu-Asp-Tyr, at pH 12. 5 will be_______ (Integer answer)

Q60.Gaseous cyclobutene isomerizes to butadiene in a first order process which has a 'K' value of 3 . 3 × 10-4 s-1 at 153°C . The time in minutes it takes for the isomerization to proceed 40% to completion at this temperature is_____. (Rounded off to the nearest integer)

Q61.If the real part of the complex number (1 −cos θ + 2i sin θ)−1 is 15 for θ ∈(0, π), then the value of the x dx is equal to: integral ∫θ0 sin JEE Main 2021 (20 Jul Shift 2) JEE Main Previous Year Paper (1) 1 (2) 2 (3) −1 (4) 0

Q61.The set of all values of k > −1, for which the equation + + 4x + 3)(3x2 + 4x + 2)+ k(3x2 + 4x + 2) = 0 has real roots, is: (3x2 + 4x + 3) 2 −(k 2 1)(3x2 (1) [−12 , 1) (2) (1, 25 ] (3) ( 12 , 32 ] −{1} (4) [2, 3)

Q61.The number of pairs 𝑎, 𝑏 of real numbers, such that whenever 𝛼 is a root of the equation 𝑥2 + 𝑎𝑥+ 𝑏= 0, 𝛼2 - 2 is also a root of this equation, is : (1) 6 (2) 8 (3) 4 (4) 2

Q61.The number of seven digit integers with sum of the digits equal to 10 and formed by using the digits 1, 2 and 3 only is: (1) 77 (2) 82 (3) 42 (4) 35

Q61.Let α = max{82 sin 3x ⋅44 cos 3x} and β = min sin 3x ⋅44 cos 3x}. If 8x2 + bx + c = 0 is a quadratic equation x∈R x∈R{82 whose roots are α1/5 and β1/5, then the value of c −b is equal to : (1) 42 (2) 47 (3) 43 (4) 50 JEE Main 2021 (27 Jul Shift 2) JEE Main Previous Year Paper