Practice Questions

Q21.A 5 V battery with internal resistance 2Ω and a 2 V battery with internal resistance 1Ω are connected to a 10Ω resistor as shown in the figure. The current in the 10Ω resistor is JEE Main 2008 JEE Main Previous Year Paper (1) 0.27AP2 to P1 (2) 0.03AP1 to P2 (3) 0.03AP2 to P1 (4) 0.27 APP1 to P2

Q24.Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross sectional area A = 10 cm2 and length = 20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual inductance is (μ0 = 4π × 10−7TmA−1) (1) 2.4π × 10−5H (2) 4.8π × 10−4H (3) 4.8π × 10−5H (4) 2.4π × 10−4H

Q25.A student measures the focal length of convex lens by putting an object pin at a distance 'u' from the lens and measuring the distance ' v ' of the image pin. The graph between ' u ' and ' v ' plotted by the student should look like (1) (2) (3) (4)

Q27.Paragraph: Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere JEE Main 2008 JEE Main Previous Year Paper constructively (see in figure). Question: Electrons accelerated by potential V are diffracted from a crystal. If d = 1Å and i = 30∘, V should be about (h = 6.6 × 10−34Js, me = 9.1 × 10−31 kg, e = 1.6 × 10−19C) (1) 2000 V (2) 50 V (3) 500 V (4) 1000 V

Q29.Paragraph: Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere JEE Main 2008 JEE Main Previous Year Paper constructively (see in figure). Question: In an experiment, electrons are made to pass through a narrow slit of width 'd' comparable to their de Broglie wavelength. They are detected on a screen at a distance ' D ' from the slit (see figure). Which of the following graph can be expected to represent the number of electrons ' N ' detected as a function of the detector position ' y ' (y = 0 corresponds to the middle of the slit)? (1) (2) (3) (4)

Q31.This question contains Statement −1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements. Statement - I: Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion. and Statement - II For heavy nuclei, binding energy per nucleon increases with increasing Z while for light nuclei it decrease with increasing Z . (1) Statement −1 is false, Statement −2 is true. (2) Statement - 1is true, Statement −2 is true; Statement −2 is correct explanation for Statement-1. (3) Statement −1 is true, Statement −2 is true; (4) Statement −1 is true, Statement −2 is False. Statement −2 is not a correct explanation for Statement-1.

Q32.A working transistor with its three legs marked P, Q and R is tested using a multimeter. No conduction is found between P and Q . By connecting the common (negative) terminal of the multimeter to R and the other (positive) terminal to P or Q , some resistance is seen on the multimeter. Which of the following is true for the transistor? (1) It is an npn transistor with R as base (2) It is a pnp transistor with R as collector (3) It is a pnp transistor with R as emitter (4) It is an npn transistor with R as collector

Q33.In the circuit below, A and B represent two inputs and C represents the output. The circuit represents (1) NOR gate (2) AND gate (3) NAND gate (4) OR gate

Q35.Two full turns of the circular scale of a screw gauge cover a distance of 1 mm on its main scale. The total number of divisions on the circular scale is 50 . Further, it is found that the screw gauge has a zero error of −0.03 mm while measuring the diameter of a thin wire, a student notes the main scale reading of 3 mm and the number of circular scale divisions in line with the main scale as 35 . The diameter of the wire is (1) 3.32 mm (2) 3.73 mm (3) 3.67 mm (4) 3.38 mm

Q37.The ionization enthalpy of hydrogen atom is 1.312 × 106Jmol−1 . The energy required to excite the electron in the atom from n = 1 to n = 2 is (1) 8.51 × 105Jmol−1 (2) 6.56 × 105Jmol−1 (3) 7.56 × 105Jmol−1 (4) 9.84 × 105Jmol−1

Q38.Which one of the following pairs of species have the same bond order? (1) CN− and NO+ (2) CN− and CN+ (3) O−2 and CN− (4) NO+ and CN+

Q39.Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below: 1 Δ⟶ 1 2 ΔassH⊖ ΔegH⊖ monH⊖ Cl2( g) ⟶ Cl(g) ⟶Cl−(g) ⟶Cl−(aq). 2 The energy involved in the conversion of 1 Cl2( g) to Cl−(g) (using the data, 2 will be Δdiss H Cl2 ⊖ = 240kJmol−1, ΔegH cl⊖ = −349kJmol−1, ΔhydH⊖Cl = −381kJmol−1) (1) +152kJmol−1 (2) −610kJmol−1 (3) −850kJmol−1 (4) +120kJmol−1

Q40.Standard entropy of X2, Y2 and XY3 are 60,40 and 50JK−1 mol−1 , respectively. For the reaction, 1 2 X2 + 32 Y2 →XY3, ΔH = −30 kJ, to be at equilibrium, the temperature will be (1) 1250 K (2) 500 K (3) 750 K (4) 1000 K

Q41.The equilibrium constants KP1 and KP2 for the reactions X ⇌2Y and Z ⇌P + Q, respectively are in the ratio of 1 : 9. If the degree of dissociation of X and Z be equal then the ratio of total pressure at these equilibria is (1) 1 : 36 (2) 1 : 1 (3) 1 : 3 (4) 1 : 9

Q43.Four species are listed below i. HCO−3 ii. H3O+ iii. HSO−4 iv. HSO3 F Which one of the following is the correct sequence of their acid strength? (1) iv < ii < iii < i (2) ii < iii < i < iv (3) i < iii < ii < iv (4) iii < i < iv < ii

Q44.The pKa of a weak acid, HA , is 4.80. The pKb of a weak base, BOH , is 4.78. The pH of an aqueous solution of the corresponding salt, BA, will be (1) 9.58 (2) 4.79 (3) 7.01 (4) 9.22

Q45.In context with the industrial preparation of hydrogen from water gas (CO + H2), which of the following is the correct statement? (1) CO and H2 are fractionally separated using (2) CO is removed by absorption in aqueous Cu2Cl2 differences in their densities solution (3) H2 is removed through occlusion with Pd (4) CO is oxidised to CO2 with steam in the presence of a catalyst followed by absorption of CO2 in alkali

Q46.Which one of the following is the correct statement? (1) Boric acid is a protonic acid (2) Beryllium exhibits coordination number of six (3) Chlorides of both beryllium and aluminium have (4) B2H6.2NH3 is known as 'inorganic benzene' bridged chloride structures in solid phase

Q47.Among the following substituted silanes the one which will give rise to cross linked silicone polymer on hydrolysis is (1) R4Si (2) RSiCl3 (3) R2SiCl2 (4) R3SiCl

Q48. The absolute configuration of is (1) S, S (2) R, R (3) R, S (4) S, R

Q50.Toluene is nitrated and the resulting product is reduced with tin and hydrochloric acid. The product so obtained is diazotised and then heated with cuprous bromide. The reaction mixture so formed contains (1) mixture of o− and p-bromotoluenes (2) mixture of o− and p-dibromobenzenes (3) mixture of o - and p-bromoanilines (4) mixture of 0 - and m -bromotoluenes

Q52.The electrophile, E⊕ attacks the benzene ring to generate the intermediate σ-complex. Of the following, which σ-complex is of lowest energy? (1) (2) (3) (4)

Q55.In a compound atoms of element Y from ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. The formula of the compound will be (1) X4Y3 (2) X2Y3 (3) X2Y (4) X3Y4

Q56.At 80∘C, the vapour pressure of pure liquid ' A ' is 520 mmHg and that of pure liquid ' B ' is 1000 mm Hg. If a mixture solution of ' A ' and ' B ' boils at 80∘C and 1 atm pressure, the amount of ' A ' in the mixture is (1 atm = 760 mmHg) (1) 52 mol percent (2) 34 mol percent (3) 48 mol percent (4) 50 mol percent

Q57.The vapour pressure of water at 20∘C is 17.5 mmHg. If 18 g of glucose (C6H12O6) is added to 178.2 g of water at 20∘C, the vapour pressure of the resulting solution will be (1) 17.675 mmHg (2) 15.750 mmHg (3) 16.500 mmHg (4) 17.325 mmHg