Practice Questions

Q24.In a fluorescent lamp choke (a small transformer) 100V of reverse voltage is produced when the choke current changes uniformly from 0.25A to 0 in a duration of 0.025ms . The self-inductance of the choke (in mH ) is estimated to be ________

Q24.A prism of angle A = 1° μ = 1. 5 . A good estimate for the minimum angle of deviation (in degrees) is close to N . Value of N is … … … 10

Q24.A galvanometer coil has 500 turns and each turn has an average area of 3 × 10−4m2 . If a torque of 1. 5 Nm is required to keep this coil parallel to a magnetic field when a current of 0. 5A is flowing through it, the strength of the field (in T) is _________ .

Q25.A point object in air is in front of the curved surface of a plano-convex lens. The radius of curvature of the curved surface is 30 cm and the refractive index of the lens material is 1.5, then the focal length of the lens (in cm) is ___________. 1 − (I) to n2

Q46.The atomic number of Unnilumium is ______.

Q46.The molarity of HNO3 in a sample which has density 1.4 g/mL and mass percentage of 63% is ________ (Molecular Weight of HNO3 = 63 ) JEE Main 2020 (09 Jan Shift 1) JEE Main Previous Year Paper

Q47.The magnitude of work done by a gas that undergoes a reversible expansion along the path ABC shown in the figure is _________. JEE Main 2020 (08 Jan Shift 1) JEE Main Previous Year Paper

Q47.The minimum number of moles of O2 required for complete combustion of 1 mole of propane and 2 moles of butane is..............

Q47.A cylinder containing an ideal gas ( 0.1mol of 1.0dm3 ) is in thermal equilibrium with a large volume of 0.5 molal aqueous solution of ethylene glycol at its freezing point. If the stoppers S1 and S2 (as shown in the figure) are suddenly withdrawn, the volume of the gas in litres after equilibrium is achieved will be _____________. (Given, Kf(water) = 2.0Kkgmol−1, R = 0.08dm3atmK−1mol−1)

Q47.The work function of sodium metal is 4. 41 × 10−19J. If photons of wavelength 300 nm are incident on the metal, the kinetics energy of the ejected electrons will be (h = 6. 63 × 10−34J s; c = 3 × 108 m s−1) __________ ×10−21J

Q47.At constant volume, 4 mol of an ideal gas when heated from 300K to 500K changes its internal energy by 5000J. The molar heat capacity at constant volume is ________ JEE Main 2020 (08 Jan Shift 2) JEE Main Previous Year Paper

Q48.An oxidation-reduction reaction in which 3 electrons are transferred has a ΔG0 of 17. 37 kJ mol−1 at 25°C. The value of Eocell (in V) is _______ ×10−2 . (1F = 96500 C mol−1)

Q49.The volume (in mL ) of 0. 1 N NaOH required to neutralise 10 mL of 0. 1 N phosphinic acid is ____________.

Q49.The oxidation states of transition metal atoms in K2 Cr2 O7, KMnO4 and K2 FeO4, respectively, are x, y and z . The sum of x, y and z is______ JEE Main 2020 (02 Sep Shift 2) JEE Main Previous Year Paper

Q50.The number of chiral centres present in threonine is _________

Q72.Set A has melements and set B has nelements. If the total number of subsets of A is 112 more than the total number of subsets of B, then the value of m ⋅n is___.

Q72.Let X = {n ∈N : 1 ≤n ≤50}. If A = {n ∈X : n is a multiple of 2} and B = {n ∈X : n is a multiple of 7}, then the number of elements in the smallest subset of X , containing both A and B , is.

Q73.The sum ∑20k=1(1 + 2 + 3 + … + k) is ___________.

Q35.An ideal gas is allowed to expand from 1 L to 10 L against a constant external pressure of 1 bar. The work done in kJ is: (1) +10.0 (2) -2.0 (3) -0.9 (4) -9.0

Q36.Consider the reversible isothermal expansion of an ideal gas in a closed system at two different temperatures T1 and T2T1 < T2 . The correct graphical depiction of the dependence of work done w vs the final volume V is: (1) (2) (3) (4) Q37.20 ml of 0.1 M H2SO4 solution is added to 30 mL of 0 .2 M NH4OH solution. The pH of the resultant mixture is: pkb of NH4OH = 4 .7 (1) 5.0 (2) 5.2 (3) 9.4 (4) 9.0 JEE Main 2019 (09 Jan Shift 1) JEE Main Previous Year Paper

Q40.The volume strength of 1M H2O2 is: (Molar mass of H2O2 = 34 g mol−1 ) (1) 5.6 (2) 22.4 (3) 11.2 (4) 16.8

Q45. K2HgI4 is 40% ionised in aqueous solution. The value of its van't Hoff factor (i) is: (1) 1.6 (2) 1.8 (3) 20 (4) 22

Q36.A solid XY kept in an evacuated sealed container undergoes decomposition to form a mixture of gases X and Y at temperature T. The equilibrium pressure is 10 bar in this vessel. Kp for this reaction is? (1) 25 (2) 100 (3) 10 (4) 5

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

Q25.Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be (1) 2 (2) 3 (3) 5 (4) 6