Practice Questions

Q10.A particle of mass m and charge q has an initial velocity →v= v0ˆj . If an electric field E = E0ˆi and magnetic → field B = B0ˆi act on the particle, its speed will double after a time (1) 2mv0 (2) 3mv0 qE0 qE0 (3) √3mv0 (4) √2mv0 qE0 qE0

Q11.Two identical electric point dipoles have dipole have dipole moments →p1 = pˆi and →p2 = −pˆi and are held on the x-axis at distance ' a ' from each other. When released, they move along the x-axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is ' m', their speed when they are infinitely far apart is : (1) P 1 (2) P 1 a √ πε0 ma a √ 2πε0 ma (3) P 2 (4) P 3 a √ πε0 ma a √ 2πε0 ma

Q12.A capacitor is made of two square plates each of side ‘ a ’ making a very small angle α between them, as shown in figure. The capacitance will be close to: (1) ∈0a2 d (1 −αa2d ) (2) ∈0a2d (1 −αa4d ) (3) ∈0a2 d (1 + αad ) (4) ∈0a2d (1 −3αa2d )

Q12.A particle of charge q and mass m is moving with a velocity −vˆi(v ≠0) → Y −Z plane at distance d. If there is magnetic field B = B0ˆk, the minimum value of v for which the particle will not hit the screen is : (1) qdB0 (2) 2qdB0 3m m (3) qdB0 (4) qdB0 m 2m

Q12.The figure shows a region of length ' 𝓁 ' with a uniform magnetic field of 0. 3 T in it and a proton entering the region with velocity 4 × 105 m s−1 making an angle 60° with the field. If the proton completes 10 revolution by the time it cross the region shown, ' 𝓁 ' is close to (mass of proton = 1. 67 × 10−27 kg, charge of the proton = 1. 6 × 10−19 C) (1) 0. 11 m (2) 0. 88 m (3) 0. 44 m (4) 0. 22 m

Q13.A wire carrying current I is bent in the shape ABCDEFA as shown, where rectangle ABCDA and ADEFA are perpendicular to each other. If the sides of the rectangles are of lengths a and b, then the magnitude and direction of magnetic moment of the loop ABCDEFA is : abI along + + ˆk ) (2) ˆk ) (1) √2abI along ( √2ˆj √2 ( √2ˆj √2 + + 2ˆk ) (4) ˆk ) (3) √2abI along ( √5ˆj √5 abI along ( √5ˆj √5

Q15.A circular coil has moment of inertia 0. 8 kg m2 around any diameter and is carrying current to produce a magnetic moment of 20 Am2 . The coil is kept initially in a vertical position and it can rotate freely around a horizontal diameter. When a uniform magnetic field of 4 T is applied along the vertical, it starts rotating around its horizontal diameter. The angular speed the coil acquires after rotating by 60o will be : (1) 10 rad s−1 (2) 10π rad s−1 (3) 20π rad s−1 (4) 20 rad s−1

Q16.A square loop of side 2a and carrying current I is kept in xz plane with its centre at origin. A long wire carrying the same current I is placed parallel to z-axis and passing through point (0, b, 0), (b >> a). The magnitude of torque on the loop about z-axis will be : (1) 2μ0I2a2 (2) 2μ0I2a2b πb π(a2+b2) (3) μ0I2a2b (4) μ0I2a2 2π(a2+b2) 2πb

Q18.You are given that 73Li = 7. 0160u,Mass of Mass of 42He = 4. 0026u and Mass of 11He = 1. 0079H When 20g of 73Li is converted into 42 He by proton capture, the energy liberated, (in kWh ), is : [Mass of nucleon = 1 GeV /c2 ] (1) 4. 5 × 105 (2) 8 × 106 (3) 6. 82 × 105 (4) 1. 33 × 106

Q19.Given the masses of various atomic particles mP = 1, 0072 u , mn = 1, 0087 u , me = 0 .000548 u , mv = 0 , ¯¯md = 2 .0141 u , where p =proton, n ≡neutron, e ≡electron, v ≡antineutrino and d ≡deuteron. Which of the following process is allowed by momentum and energy conservation : ¯(1) n + n → deuterium atom (electron bound to the (2) p →n + e+ + v nucleus) (3) n + p →d + γ (4) e+ + e−→γ

Q27.Consider the hypothetical situation where the azimuthal quantum number, 𝓁 , takes values 0, 1, 2, … … . . n + 1. Where n is the principal quantum number. Then, the element with atomic number: (1) 9 is the first alkali metal (2) 13 has a half-filled valence subshell (3) 8 is the first noble gas (4) 6 has a 2p-valence subshell JEE Main 2020 (03 Sep Shift 2) JEE Main Previous Year Paper

Q29.Among the compounds A and B with molecular formula C9H18O3, A is having higher boiling point than B. The possible structures of A and B are: JEE Main 2020 (08 Jan Shift 2) JEE Main Previous Year Paper (1) (2) (3) (4)

Q33.An organic compound ' A ' (C9H10O) when treated with conc. HI undergoes cleavage to yield compound ' B ' and ' C'. ' B' gives yellow precipitate with AgNO3 where as ' C ' tautomerizes to ' D '. ' D ' gives positive iodoform test. ' A' could be: (1) (2) (3) (4)

Q36.An element crystallises in a face–centred cubic (fcc) unit cell with cell edge a. The distance between the centres of two nearest octahedral voids in the crystal lattice is: (1) a (2) a √2 (3) √2a (4) a2

Q36.Let CNaCl and CBaSO4 , be the conductances (in S) measured for saturated aqueous solutions of NaCl and BaSO4 respectively, at a temperature T. Which of the following is false? (1) lonic mobilities of ions from both salts increase with T. (2) CBaSO4(T2) > CBaSO4(T1) for T2 > T1 (3) CNaCl(T2) > CNaCl(T1) for T2 > T1 (4) CNaCl ≫CBaSO4 at given T

Q39.The correct order of the spin-only magnetic moments of the following complexes is: (I) [Cr(H2O)6]Br2 (II) Na4[Fe(CN)6] (III) Na3[Fe(C2O4)3](Δ0 > P) (IV) (Et4N)2[CoCl4] (1) (III) > (I) > (IV) > (II) (2) (III) > (I) > (II) > (IV) (3) (I) > (IV) > (III) > (II) (4) (II) ≈(I) > (IV) > (III)

Q40.Complex X Of composition Cr(H2O)6Cln Has a spin only magnetic moment of 3.83 B. M. It reacts with AgNO3 And shows geometrical isomerism. The IUPAC nomenclature of X Is: JEE Main 2020 (09 Jan Shift 1) JEE Main Previous Year Paper (1) Hexaaqua chromium(III) chloride (2) Tetraaquadichlorido chromium(IV) chloride dihydrate (3) Dichloridotetraaqua chromium(IV) chloride (4) Tetraaquadichlorido chromium(III) chloride dihydrate dihydrate Q41. [Pd(F)(Cl)(Br)(I)]2− has n number of geometrical isomers. Then, the spin-only magnetic moment and crystal field stabilization energy [CFSE] of [Fe(CN)6]n−6 , respectively, are: [Note: Ignore the pairing energy] (1) 2.84 BM and −16Δ0 (2) 5.92 BM and 0 (3) 1.73 BM and −2.0Δ0 (4) 0 BM and −2.4Δ0

Q42.When neopentyl alcohol is heated with an acid, it slowly converted into an 85 : 15 mixture of alkenes A and B, respectively. What are these alkenes? (1) (2) (3) (4) Q43. [P] on treatment with Br2 / FeBr3 in CCl4 produced a single isomer C8H7O2 Br wile heating [P] with sodalime gives toluene. The compound [P] is: (1) (2) (3) (4)

Q42.The compound A in the following reactions is: (i) CH3 MgBr /H2O (i) O3 −−A → B → C + D (ii) Conc. H2 SO4 /Δ (ii) Zn /H2O (1) (2) (3) (4)

Q43.The major product [C] of the following reaction sequence will be : JEE Main 2020 (04 Sep Shift 2) JEE Main Previous Year Paper (1) (2) (3) (4)

Q43.The species that has a spin-only magnetic moment of 5. 9 BM, is : ( Td =tetrahedral) (1) [Ni(CN)4]2− (square planar) (2) [NiCl4]2−(Td) (3) Ni(CO)4(Td) (4) [MnBr4]2−(Td) JEE Main 2020 (06 Sep Shift 1) JEE Main Previous Year Paper

Q43. Three isomers A, B and C (mol. formula C8H11N ) give the following results: Dianotization (i) Hydrolyds −−A and C → P + Q → R (product of A) + S (product of C) (ii) acidation(KMnO4+H+) R has lower boiling point than S C6H5 SO2 Cl −B → alkali-insoluble product JEE Main 2020 (03 Sep Shift 2) JEE Main Previous Year Paper A, B and C, respectively are: (1) (2) (3) (4)

Q43.The correct order of the calculated spin-only magnetic moments of complexes (A) to (D) is: (A) Ni(CO)4 (B) [Ni(H2O)6]Cl2 (C) Na2[Ni(CN)4] (D) PdCl2(PPh3)2 (1) (A) ≈(C) < (B) ≈(D) (2) (C) < (D) < (B) < (A) (3) (C) ≈(D) < (B) < (A) (4) (A) ≈(C) ≈(D) < (B)

Q43.Two compounds A and B with same molecular formula (C3H6O) undergo Grignard reaction with methylmagnesium bromide to give products C and D . Products C and D show following chemical tests. JEE Main 2020 (02 Sep Shift 2) JEE Main Previous Year Paper Test C D Ceric Positive Positive ammonium nitrate Test Turbidity obtained after Turbidity obtained Lucas Test five minutes Immediately Iodoform Test Positive Negative C and D respectively are (1) (2) (3) (4)

Q44.An organic compound [A], molecular formula C10H20O2 was hydrolyzed with dilute sulphuric acid to given a carboxylic acid [B] and an alcohol [C]. Oxidation of [C] with CrO3 −H2 SO4 produced [B]. Which of the following structures are not possible for [A] (1) (2) (3) CH3 CH2 CH2 COOCH2 CH2 CH2 CH3 (4) (CH3)3 −C −COOCH2 C(CH3)3