Practice Questions

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

Q34.Shown in the figure below is a meter-bridge set up with null deflection in the galvanometer. The value of the unknown resistor R is JEE Main 2008 JEE Main Previous Year Paper (1) 13.75Ω (2) 220Ω (3) 110Ω (4) 55Ω

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

Q36.Which one of the following constitutes a group of the isoelectronic species? (1) C2−2 , O−2 , CO, NO (2) NO+, C2−2 , CN−, N2 (3) CN−, N2, O2−2 , C2−2 (4) N2, O−2 , NO+, CO

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

Q42.For the following three reactions a, b and c, equilibrium constants are given: a. CO(g) + H2O(g) ⇌CO2( g) + H2( g); K1 b. CH4( g) + H2O(g) ⇌CO(g) + 3H2( g); K2 c. JEE Main 2008 JEE Main Previous Year Paper CH4( g) + 2H2O(g) ⇌CO2( g) + 4H2( g); K3 Which of the following relations is correct? (1) K1√K2 = K3 (2) K2 K3 = K1 (3) K3 = K1 K2 (4) K3 ⋅K32 = K21

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

Q49.The correct decreasing order of priority for the functional groups of organic compounds in the IUPAC system of nomenclature is JEE Main 2008 JEE Main Previous Year Paper (1) −COOH, −SO3H, −CONH2, −CHO (2) −SO3H, −COOH, −CONH2, −CHO (3) −CHO, −COOH, −SO3H, −CONH2 (4) −CONH2, −CHO, −SO3H, −COOH

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

Q51.In the following sequence of reactions, the alkene affords the compound ' B ' O3 H2O CH3CH = CHCH3 ⟶A Zn B. The compound B is (1) CH3CH2CHO (2) CH3COCH3 (3) CH3CH2COCH3 (4) CH3CHO

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)

Q53.The treatment of CH3MgX with CH3C ≡C −H produces (1) (2) CH3 −CH = CH2 (3) (4)

Q54.Identify the wrong statements in the following: JEE Main 2008 JEE Main Previous Year Paper (1) Chlorofluorocarbons are responsible for ozone (2) Greenhouse effect is responsible for global layer depletion warming (3) Ozone layer does not permit infrared radiation (4) Acid rains is mostly because of oxides of from the sun to reach the earth nitrogen and sulphur

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