Practice Questions

Q22.A fully charged capacitor C with initial charge q0 is connected to a coil of self inductance L at t = 0 . The time at which the energy is stored equally between the electric and the magnetic field is : (1) π √LC (2) 2π√LC 4 (3) √LC (4) π√LC

Q23.Let the x −z plane be the boundary between two transparent media. Medium 1 in z ≥0 has a refractive index of √2 and medium 2 with z < 0 has a refractive index of √3 . A ray of light in medium 1 given by the vector →A = 6√3^i + 8√3^j −10^k is incident on the plane of separation. The angle of refraction in medium 2 is (1) 45∘ (2) 60∘ (3) 75∘ (4) 30∘

Q24.A car is fitted with a convex side-view mirror of focal length 20 cm. A second car 2.8 m behind the first car is overtaking the first car at relative speed of 15 m/s. The speed of the image of the second car as seen in the mirror of the first one is : JEE Main 2011 JEE Main Previous Year Paper (1) 1 m/s (2) 10 m/s 15 (3) 15 m/s (4) 101 m/s

Q25.Direction: The question has a paragraph followed by two statements, Statement −1 and statement −2. Of the given four alternatives after the statements, choose the one that describes the statements. A thin air film is formed by putting the convex surface of a plane - convex lens over a plane glass plate. With monochromatic light, this film gives an interference pattern due to light reflected from the top (convex) surface and the bottom (glass plate) surface of the film. Statement-1 : When light reflects from the air-glass plate interface, the reflected wave suffers a phase change of π. Statement-2 : The centre of the interference pattern is dark. (1) Statement-1 is true, Statement-2 is true; (2) Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-2 is not the correct explanation of Statement-1. Statement-1. (3) Statement- 1 is false. Statement- 2 is true. (4) Statement-1 is true, Statement- 2 is false.

Q26.This question has Statement −1 and Statement −2. Of the four choices given after the statements, choose the one that best describes the two statements. Statement-1 : A metallic surface is irradiated by a monochromatic light of frequency v > v0 (the threshold frequency). The maximum kinetic energy and the stopping potential are Kmax and V0 respectively. If the frequency incident on the surface doubled, both the Kmax and V0 are also doubled. Statement-2 : The maximum kinetic energy and the stopping potential of photoelectrons emitted from a surface are linearly dependent on the frequency of incident light. (1) Statement-1 is true, Statement-2 is true; (2) Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-2 is not the correct explanation of Statement-1. Statement-1. (3) Statement-1 is false, Statement-2 is true. (4) Statement-1 is true, Statement-2 is false.

Q28.The half life of a radioactive substance is 20 minutes. The approximate time interval (t2 −t1) between the time t2 when 23 of it has decayed and time t1 and 31 of it had decayed is : (1) 14 min (2) 20 min (3) 28 min (4) 7 min

Q32.The magnetic moment (spin only) of [NiCl4]2− is (1) 5.46BM (2) 2.83BM (3) 1.41BM (4) 1.82BM

Q33.A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emissions is at 680 nm, the other is at: (1) 325 nm (2) 743 nm (3) 518 nm (4) 1035 nm

Q35.Which of the following statement is wrong? (1) Nitrogen cannot form dπ −pπ bond. (2) Single N −N bond is weaker than the single P −P bond, (3) N2O4 has two resonance structures (4) The stability of hydrides increases from NH3 to BiH3 in group 15 of the periodic table

Q37.The hybridization of orbitals of N atom in NO−3 , NO+2 and NH+4 are respectively : (1) sp2, sp, sp3 (2) sp, sp3, sp2 (3) sp2, sp3, sp (4) sp, sp2, sp3 Q38.'a' and 'b' are van der Waals' constants for gases. Chlorine is more easily liquefied than ethane because (1) a and b for Cl2 < a and b for C2H6 (2) a for Cl2 < a for C2H6 but b for Cl2 > b for C2H6 (3) a for Cl2 > a for C2H6 but b for Cl2 < b for (4) a and b for Cl2 > a and b for C2H6 C2H6 JEE Main 2011 JEE Main Previous Year Paper

Q40.A vessel at 1000 K contains CO2 with a pressure of 0.5 atm. Some of the CO2 is converted into CO on the addition of graphite. If the total pressure at equilibrium is 0.8 atm, the value of K is (1) 3 atm (2) 0.3 atm (3) 0.18 atm (4) 1.8 atm

Q41.Boron cannot form which one of the following anions? (1) BH−4 (2) B(OH)−4 (3) BO−2 (4) BF3−6

Q43.Which of the following reagents may be used to distinguish between phenol and benzoic acid ? (1) Tollen's reagent (2) Molisch reagent (3) Neutral FeCl3 (4) Aqueous NaOH

Q45.Ozonolysis of an organic compound gives formaldehyde as one of the products. This confirms the presence of : (1) a vinyl group (2) an isopropyl group (3) an acetylenic triple bond (4) two ethylenic double bonds

Q47.The degree of dissociation (α) of a weak electrolyte, AxBy is related to van't Hoff factor (i) by the expression: (1) α = x+y+1i−1 (2) α = x+y−1i−1 (3) α = x+y+1i−1 (4) α = (x+y−1)i−1

Q48.Ethylene glycol is used as an antifreeze in a cold climate. Mass of ethylene glycol which should be added to 4 kg of water to prevent it from freezing at −6∘C will be : [Kt for water = 1.86 K kg mol−1 , and molar mass of ethylene glycol = 62 g mol−1 ) (1) 204.30 g (2) 400.00 g (3) 304.60 g (4) 804.32 g JEE Main 2011 JEE Main Previous Year Paper

Q49.The reduction potential of hydrogen half cell will be negative if : (1) p (H2) = 1 atm and [H+] = 1.0M (2) p (H2) = 2 atm and [H+] = 1.0M (3) p (H2) = 2 atm and [H+] = 2.0M (4) p (H2) = 1 atm and [H+] = 2.0M

Q51.Which of the following statements regarding sulphur is incorrect? (1) The vapour at 200∘C consists mostly of S8 rings (2) At 600∘C the gas mainly consists of S2 molecules (3) The oxidation state of sulphur is never less than (4) S2 molecule is paramagnetic. +4 in its compounds

Q53.In context of the lanthanoids, which of the following statements is not correct ? (1) All the members exhibit +3 oxidation state (2) Because of similar properties the separation of lanthanoids is not easy. (3) Availability of 4f electrons results in the (4) There is a gradual decrease in the radii of the formation of compounds in +4 state for all the members with increasing atomic number in the members of the series. series.

Q54.The outer electron configuration of Gd (Atomic No : 64 is : (1) 4f 85d06s2 (2) 4f 45d46s2 (3) 4f 75d16s2 (4) 4f 34d56s2

Q55.Which of the following facts about the complex [Cr(NH3)6]Cl3 s wrong ? (1) The complex is paramagnetic (2) The complex is an outer orbital complex (3) The complex gives white precipitate with silver (4) The complex involves d2sp3 hybridization and is nitrate solution octahedral in shape.

Q56.Phenol is heated with a solution of mixture of KBr and KBrO3 . The major product obtained in the above reaction is (1) 3-Bromophenol (2) 4-Bromophenol (3) 2, 4, 6- Tribromophenol (4) 2-Bromophenol

Q58.Trichloroacetaldehyde was subjected to Cannizzaro's reaction by using NaOH. The mixture of the products contains sodium trichloroacetate and another compound. The other compound is : JEE Main 2011 JEE Main Previous Year Paper (1) Trichloromethanol (2) 2, 2, 2-Trichloropropanol (3) Chloroform (4) 2, 2, 2-Trichloroethanol

Q61.Let α, β be real and z be a complex number. If z2 + αz + β = 0 has two distinct roots on the line Re z = 1, then it is necessary that (1) β ∈(−1, 0) (2) |β| = 1 (3) β ∈(1, ∞) (4) β ∈(0, 1)

Q63.This question has Statement −1 and Statement −2. Of the four choices given after the statements, choose the one that best describes the two statements. Statement - 1 : The number of ways of distributing 10 identical balls in 4 distinct boxes such that no box is empty is 9C3 Statement-2: The number of ways of choosing any 3 places from 9 different places is 9C3 . (1) Statement −1 is true, Statement −2 is true; (2) Statement −1 is true, Statement −2 is false. Statement −2 is not a correct explanation for Statement −1 (3) Statement −1 is false, Statement- 2 is true. (4) Statement −1 is true, Statement −2 is true; Statement −2 is a correct explanation for Statement −1