Practice Questions

Q28.The half life of a radioactive substance is 5 years. After x years a given sample of the radioactive substance gets reduced to 6. 25% of its initial value. The value of x is ____

Q28.In a Young's double slit experiment, an angular width of the fringe is 0. 35° on a screen placed at 2 m away for particular wavelength of 450 nm . The angular width of the fringe, when whole system is immersed in a medium of refractive index 7 , is 1 . The value of α is _____ . α 5

Q29.In a Young's double slit experiment, a laser light of 560 nm produces an interference pattern with consecutive bright fringes' separation of 7 . 2 mm. Now another light is used to produce an interference pattern with consecutive bright fringes' separation of 8 . 1 mm. The wavelength of second light is _____ nm .

Q29.The energy band gap of semiconducting material to produce violet (wavelength = 4000 Å) LED is _____ eV. (Round off to the nearest integer).

Q29.A 8V Zener diode along with a series resistance 𝑅 is connected across a 20 V supply (as shown in the figure). If the maximum Zener current is 25 mA, then the minimum value of 𝑅 will be _____ Ω.

Q30.If the potential barrier across a p −n junction is 0. 6 V. Then the electric field intensity, in the depletion region having the width of 6 × 10−6 m , will be _____ ×105 N C−1

Q51.On complete combustion 0. 30 g of an organic compound gave 0. 20 g of carbon dioxide and 0. 10 g of water. The percentage of carbon in the given organic compound is____(Nearest Integer)

Q52.When the excited electron of a H atom from n = 5 drops to the ground state, the maximum number of emission lines observed are

Q52.Consider the following set of quantum numbers. n l m1 A 3 3 −3 B 3 2 −2 C 2 1 +1 D 2 2 +2 JEE Main 2022 (27 Jun Shift 2) JEE Main Previous Year Paper The number of correct sets of quantum numbers is

Q52.The hybridization of P exhibited in PF5 is spx dy . The value of y is Q53. 4. 0 L of an ideal gas is allowed to expand isothermally into vacuum until the total volume is 20 L. The amount of heat absorbed in this expansion is L atm.

Q52.The moles of methane required to produce 81 g of water after complete combustion is____ ×10−2 mol. [nearest integer]

Q53.If the solubility product of PbS is 8 × 10−28 , then the solubility of PbS in pure water at 298 K is x × 10−16 mol L−1 . The value of x is____ (Nearest integer) [Given √2 = 1. 41]

Q53.A rigid nitrogen tank stored inside a laboratory has a pressure of 30 atm at 06: 00 am when the temperature is 27 °C. At 03: 00pm, when the temperature is 45 °C, the pressure in the tank will be _____ atm. [nearest integer]

Q53.Kjeldahl's method was used for the estimation of nitrogen in an organic compound. The ammonia evolved from 0. 55 g of the compound neutralised 12. 5 mL of 1M H2 SO4 solution. The percentage of nitrogen in the compound is (Nearest integer)

Q54.At 600 K, 2 mol of NO are mixed with 1 mol of O2 . 2 NO(g) + O2(g) ⇄2 NO2(g) The reaction occurring as above comes to equilibrium under a total pressure of 1 atm. Analysis of the system shows that 0. 6 mol of oxygen are present at equilibrium. The equilibrium constant for the reaction is____.

Q54. pH value of 0. 001 MNaOH solution is

Q54.A 2. 0 g sample containing MnO2 is treated with HCl liberating Cl2 . The Cl2 gas is passed into a solution of KI and 60. 0 mL of 0. 1 MNaS2 O3 is required to titrate the liberated iodine. The percentage of MnO2 in the sample is____. Nearest integer) [Atomic masses (in u) Mn = 55; Cl = 35. 5 : O = 16, I = 127, Na = 23, K = 39, S = 32 ]

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.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

Q57.The total number of monobromo derivatives formed by the alkanes with molecular formula C5H12 is (excluding stereo isomers)

Q57.In the presence of sunlight, benzene reacts with Cl2 to give product, X . The number of hydrogens in X is

Q58.The amount of charge in F (Faraday) required to obtain one mole of iron from Fe3 O4 is ______. (Round off the answer to the nearest integer)

Q58.(a) Baryte, (b) Galena, (c) Zinc blende and (d) Copper pyrites. How many of these minerals are sulphide based?

Q59.The conductivity of a solution of complex with formula CoCl3 (NH3)4 corresponds to 1 : 1 electrolyte, then the primary valency of central metal ion is

Q59.The number of statement(s) correct from the following for Copper is/are JEE Main 2022 (27 Jun Shift 1) JEE Main Previous Year Paper (A) Cu(II) complexes are always paramagnetic (B) Cu(I) complexes are generally colourless (C) Cu(I) is easily oxidized (D) In Fehling solution, the active reagent has Cu(I)