Practice Questions

Q52.A source of monochromatic radiation wavelength 400 nm provides 1000 J of energy in 10 seconds. When this radiation falls on the surface of sodium, x × 1020 electrons are ejected per second. Assume that wavelength 400 nm is sufficient for ejection of electron from the surface of sodium metal. The value of x is ______. (Nearest integer) h = 6 . 626 × 10-34 Js

Q52.The number of chlorine atoms in 20 mL of chlorine gas at STP is _______ 1021 . (Round off to the Nearest Integer). [Assume chlorine is an ideal gas at STP R = 0. 083 L bar mol−1 K−1, NA = 6. 023 × 1023]

Q52. AB3 is an interhalogen T-shaped molecule. The number of lone pairs of electrons on A is (Integer answer)

Q52.Five moles of an ideal gas at 293 K is expanded isothermally from an initial pressure of 2. 1 MPa to 1. 3 MPa against at constant external pressure 4. 3 MPa. The heat transferred in this process is ___ kJmol−1 . (Rounded-off to the nearest integer) [ Use R = 8. 314 J mol−1 K−1 ]

Q52.The mole fraction of a solute in a 100 molal aqueous solution ________ ×10−2. (Round off to the Nearest Integer). [Given : Atomic masses: H : 1. 0 u, O : 16. 0 u ]

Q52.In gaseous triethyl amine the ′′−C −N −C −′′ bond angle is ____ degree.

Q52.The number of photons emitted by a monochromatic (single frequency) infrared range finder of power 1 mW and wavelength of 1000 nm, in 0. 1 second is x × 1013 . The value of x is (Nearest integer) (h = 6. 63 × 10−34 Js, c = 3. 00 × 108 ms−1):

Q52.Complete combustion of 3 g of ethane gives x × 1022molecules of water. The value of x is ______ (Round off to the Nearest Integer). [Use : NA = 6. 023 × 1023; Atomic masses in u : C : 12. 0 ; O : 16. 0 ; H : 1. 0]

Q52.An accelerated electron has a speed of 5 × 106 ms−1 with an uncertainty of 0. 02%. The uncertainty in finding its location while in motion is x × 10−9 m. The value of x is __________. (Nearest integer) [Use mass of electron = 9. 1 × 10−31 kg, h = 6. 63 × 10−34 Js, π = 3. 14]

Q52.The number of lone pairs of electrons on the central I atom in I−3 is JEE Main 2021 (20 Jul Shift 1) JEE Main Previous Year Paper

Q52.According to molecular orbital theory, the number of unpaired electron(s) in O22 - is _________ .

Q52.A certain gas obeys P(Vm −b) = RT. The value of ( ∂P∂Z )T is RTxb . The value of x is (Integer answer) ( Z : compressibility factor)

Q52.A 6. 50 molal solution of KOH(aq. ) has a density of 1. 89 g cm−3 . The molarity of the solution is mol dm−3 . (Round off to the Nearest Integer). [Atomic masses: K : 39. 0 u; O : 16. 0 u; H : 1. 0 u]

Q53.For a chemical reaction A + B = C + D (ΔrHΘ = 80 kJ mol−1) the entropy change ΔrSΘ depends on the temperature T (in K) as ΔrSΘ = 2T(JK−1 mol−1) . Minimum temperature at which it will become spontaneous is K. (Integer)

Q53. A3B2 is a sparingly soluble salt of molar mass M(g mol−1) and solubility x g L−1. The solubility product The value of a is __________ . (Integer answer) satisfies Ksp = a( Mx ) 5.

Q53.The ionization enthalpy of Na+ formation from Na(g) is 495. 8 kJ mol−1, while the electron gain enthalpy of Br is −325. 0 kJ mol−1 . Given the lattice enthalpy of NaBr is −728. 4 kJ mol −1 . The energy for the formation of NaBr ionic solid is (−)_____10−1 kJ mol−1 Q54. 0. 4 g mixture of NaOH, Na2 CO3 and some inert impurities was first titrated with 10N HCl using phenolphthalein as an indicator, 17. 5 mL of HCl was required at the end point. After this methyl orange was added and titrated. 1. 5 mL of same HCl was required for the next end point. The weight percentage of Na2 CO3 in the mixture is (Rounded-off to the nearest integer)

Q53.An LPG cylinder contains gas at a pressure of 300 kPa at 27°C. The cylinder can withstand the pressure of 1. 2 × 106 Pa . The room in which the cylinder is kept catches fire. The minimum temperature at which the bursting of cylinder will take place is __________ ∘C. (Nearest integer)

Q53.The difference between bond orders of CO and NO⊕ is x2 where x = (Round off to the Nearest Integer)

Q53.The Born-Haber cycle for KCl is evaluated with the following data: ΔfHΘ for KCl = −436.7 kJmol−1; ΔsubHΘ for K = 89.2 kJmol−1; Δionization HΘ for K = 419.0 kJ mol −1; Δelectron gain HΘ for Cl(g) = −348.6 kJmol−1 Δbond HΘ for Cl2 = 243.0 kJmol−1 The magnitude of lattice enthalpy of KCl in kJmol−1 is (Nearest integer)

Q53. AX is a covalent diatomic molecule where A and X are second row elements of periodic table. Based on Molecular orbital theory, the bond order of AX is 2. 5. The total number of electrons in AX is_____. (Round off to the Nearest Integer).

Q53.Consider the reaction N2O4( g) ⇌2 NO2( g) The temperature at which KC = 20. 4 and KP = 600. 1, is ______ K. (Round off to the Nearest Integer). [Assume all gases are ideal and R = 0. 0831 L bar K−1 mol−1]

Q53.When 400 mL of 0. 2 M H2 SO4 solution is mixed with 600 mL of 0. 1 MNaOH solution, the increase in temperature of the final solution is — × 10−2 K . (Round off to the nearest integer). [Use : H+(aq) + OH−(aq) →H2O :ΔγH = −57. 1 kJ mol−1] Specific heat of H2O = 4. 18 J K−1 g−1 , density of H2O = 1. 0 g cm−3 Assume no change in volume of solution on mixing.

Q53.The number of f electrons in the ground state electronic configuration of Np(Z = 93) is ______ .(Integer answer)

Q53.Consider titration of NaOH solution versus 1. 25 M oxalic acid solution. At the end point following burette readings were obtained. (i) 4. 5 mL (ii) 4. 5 mL (iii) 4. 4 mL (iv) 4. 4 mL (v) 4. 4 mL If the volume of oxalic acid taken was 10. 0 mL then the molarity of the NaOH solution is ___ M. (Rounded- off to the nearest integer)

Q53.The volume occupied by 4. 75 g of acetylene gas at 50°C and 740 mm Hg pressure is ____________ L. (Rounded off to the nearest integer) [Given R = 0. 0826 L atm K−1 mol−1 ]