Practice Questions

Q47.A molecule M associates in a given solvent according to the equation M ⇌(M)n . For a certain concentration of M, the van't Hoff factor was found to be 0.9 and the fraction of associated molecules was 0.2. The value of n is: (1) 3 (2) 5 (3) 2 (4) 4

Q47. Cu+/Cu = +0.52 V, Fe3+/Fe2+ = +0.77 V, Electrode potentials (E∘) are given below : 1 Based on the above potentials, strongest I2( s)/I−= +0.54 V, 2 Ag+/Ag = +0.88 V. oxidizing agent will be : JEE Main 2013 (09 Apr Online) JEE Main Previous Year Paper (1) Cu+ (2) Fe3+ (3) Ag+ (4) I2

Q50.The rate of a reaction doubles when its temperature changes from 300K to 310K. Activation energy of such a reaction will be: ​ (R = 8.314 JK−1 mol−1 and log 2= 0.301) JEE Main 2013 (07 Apr) JEE Main Previous Year Paper (1) 58. 5 kJ mol −1 (2) 60. 5 kJ mol −1 (3) 53. 6 kJ mol −1 (4) 48. 6 kJ mol −1

Q50.Oxidation state of sulphur in anions SO2−3 , S2O2−4 and S2O2−6 increases in the orders : (1) S2O2−6 < S2O2−4 < SO2−3 (2) SO2−6 < S2O2−4 < S2O2−6 (3) S2O2−4 < SO2−3 < S2O2−6 (4) S2O2−4 < S2O2−6 < SO2−3

Q51.The magnetic moment of the complex anion [Cr(NO) (NH3)(CN)4]2− is : (1) 5.91BM (2) 3.87BM (3) 1.73BM (4) 2.82BM

Q59.If a polythene sample contains two monodisperse fractions in the ratio 2 : 3 with degree of polymerization 100 and 200, respectively, then its weight average molecular weight will be : (1) 4900 (2) 4600 (3) 4300 (4) 5200

Q59.A compound with molecular mass 180 is acylated with CH3 COCl to get a compound with molecular mass 390 . The number of amino groups presents per molecule of the former compound is (1) 4 (2) 6 (3) 2 (4) 5

Q47.The freezing point of a 1.00 m aqueous solution of HF is found to be −1.91∘C. The freezing point constant of water, Kf is 1.86 K kg mol−1 . The percentage dissociation of HF at this concentration is (1) 30% (2) 10% (3) 5.2% (4) 2.7%

Q48.Given E∘ = 0.34 V, E∘ = 0.15 V Cu2+/Cu Cu2+/Cu Standard electrode potential for the half cell Cu+/Cu is (1) 0.38 V (2) 0.53 V (3) 0.19 V (4) 0.49 V

Q49.The activation energy for a reaction which doubles the rate when the temperature is raised from 298 K to 308 K is (1) 59.2 kJ mol−1 (2) 39.2 kJ mol−1 (3) 52.9 kJ mol−1 (4) 29.5 kJ mol−1

Q54.The number of unpaired electrons in Gadolinium [Z = 64] is (1) 3 (2) 8 (3) 6 (4) 2

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

Q58.Given E∘ = −0.72 V, E∘ = −0.42 V. The potential for the cell Cr3+/Cr Fe2+//Fe Cr Cr3+(0.1M) Fe2+(0.01M) Fe is (1) 0.26 V (2) 0.399 V (3) −0.339 V (4) −0.26 V

Q57.How many moles of magnesium phosphate, Mg3(PO4)2 will contain 0.25 mole of oxygen atoms? (1) 0.02 (2) 3.125 × 10−2 (3) 1.25 × 10−2 (4) 2.5 × 10−2

Q58.Density of a 2.05M solution of acetic acid in water is 1.02 g/mL . The molality of the solution is (1) 1.14 mol kg−1 (2) 2.28 mol kg−1 (3) 3.28 mol kg−1 (4) 0.44 mol kg−1

Q59.According to Bohr's theory, the angular momentum of an electron in 5th orbit is (1) 25 πh (2) 1.0 πh (3) 10 πh (4) 2.5 πh