Practice Questions

Q55.The number of incorrect statement/s about the black body from the following is______ (A) Emit or absorb energy in the form of electromagnetic radiation. (B) Frequency distribution of the emitted radiation depends on temperature. (C) At a given temperature, intensity vs frequency curve passes through a maximum value. JEE Main 2023 (10 Apr Shift 1) JEE Main Previous Year Paper (D) The maximum of the intensity vs frequency curve is at a higher frequency at higher temperature compared to that at lower temperature.

Q56.The number of correct statement/s involving equilibria in physical processes from the following is ________ (A) Equilibrium is possible only in a closed system at a given temperature. (B) Both the opposing processes occur at the same rate. (C) When equilibrium is attained at a given temperature, the value of all its parameters became equal (D) For dissolution of solids in liquids, the solubility is constant at a given temperature.

Q56. The number of molecules which gives haloform test among the following molecules is :

Q56.At 27°C, a solution containing 2 . 5 g of solute in 250 . 0 mL of solution exerts an osmotic pressure of 400 Pa. The molar mass of the solute is g mol-1 (Nearest integer) (Given : R = 0 . 083 L bar -1 mol-1 )

Q56.Some amount of dichloromethane CH2Cl2 is added to 671 . 141mL of chloroform CHCl3 to prepare 2 . 6 × 10-3M solution of CH2Cl2DCM. The concentration of DCM is _____ ppm (by mass). JEE Main 2023 (30 Jan Shift 1) JEE Main Previous Year Paper Given: Atomic mass : C = 12; H: 1; Cl = 35 . 5 density of CHCl3 = 1 . 49g cm-3

Q56.Among the following the number of compounds which will give positive iodoform reaction is _____. (a) 1 -Phenylbutan- 2 -one (b) 2-Methylbutan- 2-ol (c) 3-Methylbutan- 2-ol (d) 1-Phenylethanol (e) 3, 3 -dimethylbutan- 2-one (f) 1-Phenylpropan- 2-ol

Q56.Number of bromo derivatives obtained on treating ethane with excess of Br2 in diffused sunlight is _________

Q56. The value of x in compound ‘ D’ is _____

Q56.For a reversible reaction A ⇌B, the ΔH forward reaction = 20 kJ mol–1 . The activation energy of the uncatalyzed forward reaction is 300 kJ mol–1 . When the reaction is catalysed keeping the reactant concentration same, the rate of the catalysed forward reaction at 27∘C is found to be same as that of the uncatalyzed reaction at 327∘C. The activation energy of the catalysed backward reaction is _______ kJ mol–1 . Q57. 20 mL of 0. 5 M NaCl is required to coagulate 200 mL of As2 S3 solution in 2 hours. The coagulating value of NaCl is ___________.

Q57.The mass of NH3 produced when 131. 8 kg of cyclohexane carbaldehyde undergoes Tollen’s test is _____ kg. (Nearest Integer) Molar mass of C = 12 g/ mol N = 14 g/ mol O = 16 g/ mol

Q57.Sodium metal crystallises in a body centred cubic lattice with unit cell edge length of 4 Å. The radius of sodium atom is ___ × 10-1Å. (Nearest integer)

Q57.Mass of Urea NH2CONH2 required to be dissolved in 1000 g of water in order to reduce the vapour pressure of water by 25% is _______ g . (Nearest integer) Given : Molar mass of N, C, O and H are 14, 12, 16 and 1 g mol-1 respectively.

Q57.At what pH, given half cell MnO4- (0 . 1M) ∣Mn2 + ( 0 . 001 M ) will have electrode potential of 1 . 282 V ? (Nearest Integer) Given 𝑜 + = 1 . 54 V, 2 . 303RT = 0 . 059 V EMnO4- / Mn2 F

Q57.An aqueous solution of volume 300 cm3 contains 0 . 63 g of protein. The osmotic pressure of the solution at 300 K is 1 . 29 mbar. The molar mass of the protein is gmol-1. Given : R = 0 . 083 LbarK-1 mol-1

Q57.Number of compounds giving (i) red colouration with ceric ammonium nitrate and also (ii) positive iodoform test from the following is _________ JEE Main 2023 (25 Jan Shift 2) JEE Main Previous Year Paper

Q57.The logarithm of equilibrium constant for the reaction Pd2 + + 4Cl- ⇌PdCl42 - is (Nearest integer) 2 . 303RT Given: = 0 . 06 V F Pd2 + + 2e- ⇌Pd(s) E𝑜= 0 . 83 V ( aq ) PdCl42 - (aq) + 2e- ⇌Pd(s) + 4Cl- (aq) Eo = 0 . 65 V

Q58.KClO3 + 6FeSO4 + 3H2SO4 → KCl + 3Fe2 ( SO4 ) + 3H2O 3 The above reaction was studied at 300 K by monitoring the concentration of FeSO4 in which initial concentration was 10 M and after half an hour became 8 . 8 M. The rate of production of Fe2 ( SO4 ) is 3 _______ × l0 – 6 mol L – 1 s – 1 (Nearest integer)

Q58.If the degree of dissociation of aqueous solution of weak monobasic acid is determined to be 0 . 3, then the observed freezing point will be _____ % higher than the expected/theoretical freezing point. (Nearest integer).

Q58.A and B are two substances undergoing radioactive decay in a container. The half life of A is 15 min and that of B is 5 min. If the initial concentration of B is 4 times that of A and they both start decaying at the same time, how much time will it take for the concentration of both of them to be same? ________min.

Q58.Number of compounds from the following which will not produce orange red precipitate with Benedict solution is........ Glucose, maltose, sucrose, ribose, 2-deoxyribose, amylose, lactose JEE Main 2023 (11 Apr Shift 2) JEE Main Previous Year Paper

Q58.A →B The rate constants of the above reaction at 200 K and 300 K are 0 . 03 min-1 and 0 . 05 min-1 respectively. The activation energy for the reaction is J (Nearest integer) (Given : In 10 = 2 . 3 R = 8 . 3 J K-1 mol-1 log 5 = 0 . 70 log 3 = 0 . 48 log2 = 0 . 30

Q58.Sea water contains 29 . 25 % NaCl and 19 % MgCl2 by weight of solution. The normal boiling point of the sea water is ∘C (Nearest integer) Assume 100% ionization for both NaCl and MgCl2 Given: KbH2O = 0 . 52 K kg mol-1 Molar mass of NaCl and MgCl2 is 58 . 5 and 95 g mol-1 respectively.

Q58.In Chromyl chloride, the oxidation state of chromium is (+) ___________.

Q58.If compound A reacts with B following first order kinetics with rate constant 2 . 011 × 10-3 s-1. The time taken by A (in seconds) to reduce from 7 g to 2 g will be _____ . (Nearest Integer) log5 = 0 . 698, log7 = 0 . 845, log2 = 0 . 301

Q59.In ammonium - phosphomolybdate, the oxidation state of Mo is +_______ JEE Main 2023 (06 Apr Shift 1) JEE Main Previous Year Paper