Practice Questions

Q56.A chloro compound "A". (i) forms aldehydes on ozonolysis followed by the hydrolysis. (ii) when vaporized completely 1. 53 g of A, gives 448 mL of vapour at STP. The number of carbon atoms in a molecule of compound A is Q57. 83 g of ethylene glycol dissolved in 625 g of water. The freezing point of the solution is ..... K. (Nearest integer) [Use : Molal Freezing point depression constant of water = 1. 86 K kg mol−1 Freezing point of water = 273 K Atomic masses : C : 12. 0u, O : 16. 0u, H : 1. 0u]

Q56.The reaction of sulphur in alkaline medium is given below: S8s + a OHaq−→b Saq2 −+ c S2O3aq2 −+ d H2Ol The values of '𝑎' is______ (Integer answer)

Q56.An organic compound is subjected to chlorination to get compound A using 5. 0 g of chlorine. When 0. 5 g of compound A is reacted with AgNO3 [Carius Method], the percentage of chlorine in compound A is when it forms 0. 3849 g of AgCl. (Round off to the Nearest Integer) (Atomic masses of Ag and Cl are 107. 87 and 35. 5 respectively) Q57. 1. 46 g of a biopolymer dissolved in a 100 mL water at 300 K exerted an osmotic pressure of 2. 42 × 10−3 bar The molar mass of the biopolymer is −× 104 g mol−1. (Round off to the Nearest Integer) [Use: R = 0. 083 L bar mol−1 K−1]

Q56.Using the provided information in the following paper chromatogram: JEE Main 2021 (25 Feb Shift 1) JEE Main Previous Year Paper The calculated Rf value of A is _____ × 10−1 .

Q56.At 20°C, the vapour pressure of benzene is 70 torr and that of methyl benzene is 20 torr. The mole fraction of benzene in the vapour phase at 20°C above an equimolar mixture of benzene and methyl benzene is __ × 10−2. (Nearest integer)

Q56.If a compound AB dissociates to the extent of 75% in an aqueous solution, the molality of the solution which shows a 2. 5 K rise in the boiling point of the solution is ___ molal. (Rounded-off to the nearest integer) [Kb = 0. 52K kg mol−1].

Q56.The vapour pressures of A and B at 25°C are 90 mmHg and 15 mm Hg respectively. If A and B are mixed such that the mole fraction of A in the mixture is 0. 6, then the mole fraction of B in the vapour phase is x × 10−1. The value of x is (Nearest integer)

Q56.When 10 mL of an aqueous solution of Fe2 + ions was titrated in the presence of dil H2SO4 using diphenylamine indicator, 15 mL of 0 . 02 M solution of K2Cr2O7 was required to get the end point. The molarity of the solution containing Fe2 + ions is x × 10-2 M. The value of x is ______. (Nearest integer)

Q57.For the reaction 2 Fe3+(aq) + 2I−(aq) →2 Fe2+(aq) + I2( s) the magnitude of the standard molar free energy change, ΔrG∘m = − ______ kJ (Round off to the Nearest Integer). JEE Main 2021 (18 Mar Shift 1) JEE Main Previous Year Paper Q58. 2 NO(g) + Cl2( g) ⇌2 NOCl(s) This reaction was studied at −10°C and the following data was obtained run [NO]0 [Cl2]0 r0 1 0.10 0.10 0.18 2 0.10 0.20 0.35 3 0.20 0.20 1.40 [NO]0 and [Cl2]0 are the initial concentrations and r0 is the initial reaction rate. The overall order of the reaction is (Round off to the Nearest Integer).

Q57.A KCl solution of conductivity 0. 14 S m−1 shows a resistance of 4. 19Ω in a conductivity cell. If the same cell is filled with an HCl solution, the resistance drops to 1. 03Ω . The conductivity of the HCl solution is ____ ×10−2 S m−1 . (Round off to the Nearest Integer).

Q57.For a first order reaction, the ratio of the time for 75% completion of a reaction to the time for 50% completion is ___________ . (Integer answer)

Q57.The inactivation rate of a viral preparation is proportional to the amount of virus. In the first minute after preparation, 10% of the virus is inactivated. The rate constant for viral inactivation is ___ × 10−3 min−1. (Nearest integer) [Use : ln 10 = 2. 303; log10 3 = 0. 477 property of logarithm : log xy = y log x]

Q57.Number of amphoteric compounds among the following is (A) BeO JEE Main 2021 (24 Feb Shift 1) JEE Main Previous Year Paper (B) BaO (C) BeOH2 (D) Sr OH2

Q57. Consider the above chemical reaction. The total number of stereoisomers possible for Product "P" is _________

Q57.The molar conductivity at infinite dilution of barium chloride, sulphuric arid and hydrochloric acid are 280, 860 426 Scm2 mol−1 respectively. The molar conductivity at infinite dilution of barium sulphate is ___ Scm2 mol−1 ( Round off to the Nearest Integer).

Q57.These are physical properties of an element (A) Sublimation enthalpy (B) Ionisation enthalpy (C) Hydration enthalpy (D) Electron gain enthalpy The total number of above properties that affect the reduction potential is (Integer answer)

Q57.Potassium chlorate is prepared by electrolysis of KCl in basic solution as shown by following equation. 6 OH−+ Cl−→ClO−3 + 3H2O + 6e− A current of xA has to be passed for 10 h to produce 10. 0 g of potassium chlorate. the value of x is __________. (Nearest integer) (Molar mass of KClO3 = 122. 6 g mol−1 F = 96500 C )

Q57.A certain element crystallises in a bcc lattice of unit cell edge length 27 A. If the same element under the same o conditions crystallises in the fcc lattice, the edge length of the unit cell in A will be __________. (Round off to the Nearest Integer). [Assume each lattice point has a single atom] [Assume √3 = 1. 73, √2 = 1. 41]

Q57.The magnitude of the change in oxidising power of the MnO−4 / Mn2+ couple is x × 10−4 V if the H+ concentration is decreased from 1 M to 10−4M at 25°C. (Assume concentration of MnO−4 and Mn2+ to be same on change in H+ concentration). The value of x is __________. (Rounded off to the nearest integer) [Given: 2.303 RT = 0. 059] F

Q57.In a solvent 50% of an acid HA dimerizes and the rest dissociates. The van't Hoff factor of the acid is _____ ×10−2 (Round off to the nearest integer)

Q58.The reaction 2 A + B2 →2 AB is an elementary reaction. For a certain quantity of reactants, if the volume of the reaction vessel is reduced by a factor of 3, the rate of the reaction increases by a factor of _____ . (Round off to the Nearest Integer). JEE Main 2021 (17 Mar Shift 2) JEE Main Previous Year Paper

Q58.For the reaction A →B, the rate constant k (in s-1) is given by 2 . 47 × 103 log10k = 20 . 35 - T The energy of activation in kJ mol-1 is ________ . (Nearest integer) [Given : R = 8 . 314 J K-1 mol-1]

Q58.When 3. 00 g of a substance X ' is dissolved in 100 g of CCl4 , it raises the boiling point by 0. 60 K. The molar mass of the substance ' X′ is ___ g mol−1 . (Nearest integer). [Given Kb for CCl4 is 5. 0 K kg mol−1]

Q58.The oxygen dissolved in water exerts a partial pressure of 20 kPa in the vapour above water. The molar solubility of oxygen in water is ______ ×10−5 mol dm−3. (Round off to the Nearest Integer). [Given : Henry's law constant = KH = 8. 0 × 104 kPa for O2. Density of water with dissolved oxygen = 1. 0 kg dm−3 ]

Q58.Consider the sulphides HgS, PbS, CuS, Sb2 S3, As2 S3 and CdS. Number of these sulphides soluble in 50% HNO3 is ___________ .