Practice Questions

Q55.An element M crystallises in a body centred cubic unit cell with a cell edge of 300pm. The density of the element is 6 . 0 g cm-3. The number of atoms present in 180 g of the element is____ × 1023. (Nearest integer) Q56.150 g of acetic acid was contaminated with 10 . 2 g ascorbic acid C6H8O6 to lower down its freezing point by x × 10-1°C. The value of x is____ (Nearest integer). [Given Kf = 3 . 9 K kg mol-1; Molar mass of ascorbic acid = 176 g mol-1]

Q55.Atoms of element X form hcp lattice and those of element Y occupy 32 of its tetrahedral voids. The percentage of element X in the lattice is (Nearest integer)

Q55.A company dissolves ' x ' amount of CO2 at 298 K in 1 litre of water to prepare soda water. X = ×10−3 g . (nearest integer) (Given: partial pressure of CO2 at 298 K = 0. 835 bar. Henry's law constant for CO2 at 298 K = 1. 67 kbar. Atomic mass of H, C and O is 1, 12 , and 6 g mol−1 , respectively)

Q55.The number of sp3 hybridised carbons in an acyclic neutral compound with molecular formula C4H5N is

Q55.While performing a thermodynamics experiment, a student made the following observations, HCl + NaOH →NaCl + H2OΔH = −57. 3 kJ mol−1 CH3 COOH + NaOH →CH3 COONa + H2O ΔH = −55. 3 kJ mol−1 . JEE Main 2022 (25 Jul Shift 2) JEE Main Previous Year Paper The enthalpy of ionization of CH3 COOH as calculated by the student is kJ mol−1 .

Q55.The standard entropy change for the reaction 4Fes + 3O2g →2Fe2O3s is -550 J K-1 at 298 K [Given : The standard enthalpy change for the reaction is -165 kJ mol-1]. The temperature in K at which the reaction attains equilibrium is (Nearest Integer)

Q55.A solution of Fe2SO43 is electrolyzed for 'x' min with a current of 1 . 5 A to deposit 0 . 3482 g of Fe. The value of x is - [nearest integer] Given : 1 F = 96500 Cmol-1. Atomic mass of Fe = 56 gmol-1

Q56.A sample of 0. 125 g of an organic compound when analysed by Duma's method yields 22. 78 mL of nitrogen gas collected over KOH solution at 280 K and 759 mmHg . The percentage of nitrogen in the given organic compound is____ (a) The vapour pressure of water at 280 K is 14. 2 mmHg (b) R = 0. 082 L atm K−1 mol−1 JEE Main 2022 (28 Jul Shift 2) JEE Main Previous Year Paper

Q56.A flask is filled with equal moles of A and B. The half lives of A and B are 100 s and 50 s respectively and are independent of the initial concentration. The time required for the concentration of A to be four times that of B is____ s. (Given : ln 2 = 0. 693 ) Q57. 2. 0 g of H2 gas is adsorbed on 2. 5 g of platinum powder at 300 K and 1 bar pressure. The volume of the gas adsorbed per gram of the adsorbent is mL (Given : R = 0. 083 L bar K−1 mol−1 )

Q56.The osmotic pressure of blood is 7. 47 bar at 300 K . To inject glucose to a patient intravenously, it has to be isotonic with blood. The concentration of glucose solution in gL−1 is (Molar mass of glucose = 180 g mol−1 , R = 0. 083 Lbar−1 mol−1 ) (Nearest integer)

Q56.The standard free energy change ΔG° for 50% dissociation of N2O4 into NO2 at 27 °C and 1 atm pressure is -x J mol-1. The value of x is - . . . . . J. (Nearest Integer) [Given : R = 8 . 31 J K-1 mol-1, log1 . 33 = 0 . 1239 ln10 = 2 . 3]

Q56.The number of non-ionisable protons present in the product B obtained from the following reaction is___ C2H5OH + PCl3 →C2H5Cl + A A + PCl3 →B

Q56.Assuming 1μg of trace radioactive element X with a half life of 30 years is absorbed by a growing tree. The amount of X remaining in the tree after 100 years is_____ × 10-1μg. [Given : ln10 = 2 . 303; log2 = 0 . 30]

Q56.When a certain amount of solid A is dissolved in 100 g of water at 25 °C to make a dilute solution, the vapour pressure of the solution is reduced to one-half of that of pure water. The vapour pressure of pure water is 23. 76 mmHg . The number of moles of solute A added is Q57. [A] → [B] Reactant Product If formation of compound [B] follows the first order of kinetics and after 70 minutes the concentration of [A] was found to be half of its initial concentration. Then the rate constant of the reaction is x × 10−6 s−1 . The value of x is____

Q56.In the following reaction ​ The % yield for reaction I is 60% and that of reaction II is 50%. The overall yield of the complete reaction is % Q57. 2NO + 2H2 →N2 + 2H2O The above reaction has been studied at 800 °C . The related data are given in the table below Initial Reaction serial Initial pressure of Initial rate Pressure −dp /s) number H2/ kPa ( dt )/(kPa of NO / kPa 1 65. 6 40. 0 0. 135 2 65. 6 20. 1 0. 033 3 38. 6 65. 6 0. 214 4 19. 2 65. 6 0. 106 The order of the reaction with respect to NO is____

Q56.The separation of two coloured substances was done by paper chromatography. The distances travelled by solvent front, substance A and substance B from the base line are 3. 25 cm. 2. 08 cm and 1. 05 cm . respectively. The ratio of Rf values of A to B is (Answer the nearest integer)

Q56.At 345 K, the half life for the decomposition of a sample of a gaseous compound initially at 55 . 5 kPa was 340 s. When the pressure was 27 . 8 kPa, the half life was found to be 170 s. The order of the reaction is - [integer answer]

Q56.The cell potential for the given cell at 298 K Pt|H2(g, 1 bar)| H+(aq) Cu2+(aq) Cu(s) is 0. 31 V . The pH of the acidic solution is found to be 3, whereas the concentration of Cu2+ is 10x M. The value of x is _________. (Given: EΘ = 0. 34 V and 2.303F RT = 0. 06 V ) Cu2+ / Cu JEE Main 2022 (29 Jun Shift 2) JEE Main Previous Year Paper

Q56.The vapour pressures of two volatile liquids A and B at 25 °C are 50 Torr and 100 Torr, respectively. If the liquid mixture contains 0. 3 mole fraction of A, then the mole fraction of liquid B in the vapour phase is 17x . The value of x is

Q56.In a solid AB, A atoms are in ccp arrangement and B atoms occupy all the octahedral sites. If two atoms from the opposite faces are removed, then the resultant stoichiometry of the compound is AxBy . The value of x is [nearest integer]

Q56.A radioactive element has a half life of 200 days. The percentage of original activity remaining after 83 days is____(Nearest integer) (Given : antilog 0. 125 = 1. 333, antilog 0. 693 = 4. 93) Q57. [Fe (CN)6]4− [Fe (CN)6]3− [Ti (CN)6]3− [Ni (CN)4]2− [Co (CN)6]3− Among the given complexes, number of paramagnetic complexes is

Q56.If O2 gas is bubbled through water at 303 K, the number of millimoles of O2 gas that dissolve in 1 litre of water is____(Nearest integer) (Given : Henry's Law constant for O2 at 303 K is 46. 82k bar and partial pressure of O2 = 0. 920 bar) (Assume solubility of O2 in water is too small, nearly negligible)

Q56.The cell potential for ZnZn2 + (aq)‖Snx + Sn is 0 . 801V at 298 K. The reaction quotient for the above reaction is 10-2. The number of electrons involved in the given electrochemical cell reaction is _____ . 0 0 2 . 303RT = + 0 . 008 V and = 0 . 06 V) = - 0 . 763 V, ESnx + | Sn (Given EZn2 + ∣Zn F

Q56.At 298 K, the equilibrium constant is 2 × 1015 for the reaction: Cu(s) + 2 Ag+(aq) ⇌Cu2+(aq) + 2 Ag(s) The equilibrium constant for the reaction 2 1 Cu2+(aq) + Ag(s) ⇌12 Cu(s) + Ag+(aq) is x × 10−8 . The value of x is ______. (Round off the answer to the nearest integer) JEE Main 2022 (26 Jul Shift 1) JEE Main Previous Year Paper

Q56.The resistance of a conductivity cell containing 0. 01 MKCl solution at 298 K is 1750 Ω. If the conductivity of 0. 01 MKCl solution at 298 K is 0. 152 × 10−3 S cm−1 , then the cell constant of the conductivity cell is____ ×10−3 cm−1