JEE Main Chemistry Model Questions with Answers

1. The dissociation energy of H2 is 430.53 kJ mol-1. If hydrogen is dissociated by illumination with radiation of wavelength 253.7nm, the fraction of the radiant energy which will be converted into kinetic energy is given by
A) 1.22% B) 8.76% C) 2.22% D) 100%

2. If the uncertainties in position and momentum are equal, the uncertainty in the velocity is

3. The number of concentric spherical surfaces for 3s orbital at which the probability of finding the electron is zero, are
A) 0 B) 1 C) 2 D) 3

4. Which of the following structures of hydrazoic acid molecule is not expected to be canonical form
A) I only B) II only C) both I and II D) III only

5. The C – O bond lengths in CO, CO2 and CO32- follow the order
A) CO2 > CO32- < CO B) CO32- < CO2 < CO C) CO < CO2 < CO32- D) CO < CO32- < CO2 6. H2O2 is present as …….. in alkaline medium A) HO2- ion B) H3O2+ ion C) H+ ion D) O22- ion 7. Which of the following disproportionate when treated with NaOH? A) SO3 B) F2 C) N2 D) Cl2 8. Select correct statement A) Oxides and peroxides of alkali metals are diamagnetic and colourless B) Superoxides are paramagnetic C) Li and Na do not form superoxides D) All are correct statements 9. When NaNO2 is treated with Na A) NaNO3 is formed B) Na2O and N2 are formed C) Na2O2 and N2 are formed D) Na2O and Na3N are formed 10. AlCl3 is treated with excess of NaOH forming A) Al(OH)3 B) Al2O3 C) NaAlO2 D) none of these 11. Select correct statement A) Li and Mg show diagonal relationship B) Be forms complexes [Be(C2O4)2]2- C) Al forms AIF6 3-, an octahedral complex D) All are correct statements 12. Be and Al resemble in the following but not in A) both form electron deficient hydrides B) both are rendered passive by HNO3 C) both form amphoteric oxides D) both have sp-hybridisation in their compounds 13. Select correct statement about stability of cations A) Ga3+ > In3+ > TI3+
B) TI+1 > IN+1 > Ga+1
C) TI3+ > TI+1
D) All are correct statements

14. Alum is found to contain hydrated monovalent cation [M(H2O)6]+, trivalent cation [M'(H2O)6]3+ and SO4 2- in the ratio of
A) 1 : 1 : 1 B) 1 : 2 : 3 C) 1 : 3 : 2 D) 1 : 1 : 2

15. CH2OH – CH2OH – CH2OH IUPAC name is
A) 1, 2, 3- propanol
B) 1, 2, 3 hydroxy propane
C) Propane 1, 2, 3- triol
D) glycerol

16. The decreasing order of bond lengths of carbon – oxygen bonds in
(i) H2CO (ii) H3COCH3
(iii) HCOO– (iv) CO32–
A) III > I > II > IV B) II > IV > III > I
C) I > IV > III > II D) III > I > IV > II

17. An ideal gas is at pressure P0 in a vessel. If the masses of all the molecules are halved and their rms speeds doubled, the resulting pressure P will be
A) 4P0 B) 2P0 C) P0 D) P0/2

18. In an atom two electrons move around the nucleus in circular orbits of radii R and 4R. The ratio of the time taken by them to complete one revolution is
A) 1 : 4 B) 4 : 1 C) 1 : 8 D) 8 : 7

19. The angular momentum of electron in H atom is proportional to
A) r2 B) 1/r C) r1/2 D) (1/r)1/2

20. The longest bond length containing species is
A) NO+ B) O2 - C) O2 + D) N2 +

21. The de Broglie wavelength of an electron accelerated by an electric field of V volts is given by

22. The wave number of electromagnetic radiation emitted during the transition in between two energy levels of Li2+ ion whose principal quantum number sum is 4 and difference is 2, is
A) 3.5 RH B) 4 RH C) 8 RH D) 8/9 RH

23. SO2 and He are kept in a container at partial pressures P1 and P2. A thin perforation is made in the wall of the container and it is observed that the two gases effuse out at the same rate. The ratio P1 : P2 will be
A) 16:1 B) 1:16 C) 1:4 D) 4:1

24. 190.0 ml of N2 was collected in a jar over water at some temperature, water level inside and outside the jar standing at the same height. If barometer reads 740 mm Hg and aqueous tension at the temperature of the experiment is 20 mm Hg, the volume of the gas at 1 atm pressure and at the same temperature would be
A) 185.0 ml B) 180.0 ml C) 195.0 ml D) 200 ml

25. α-Hydrogen is most acidic in

26. 3g of Mg is burnt in a closed vessel containing 3 g of oxygen. The weight of excess reactant left is
A) 0.5 g of oxygen B) 1.0 g of oxygen C) 1.0 g of Mg D) 0.5 g of Mg

27. The hydrated salt Na2CO3.x H2O undergoes 63% loss in mass on heating and becomes anhydrous. The value of x is
A) 3 B) 5 C) 7 D) 10

28. An energy of 24.6eV is required to remove one of the electrons from a helium atom. The energy required to remove both the electrons from helium atom is
A) 38.2eV B) 49.2eV C) 51.8eV D) 79.0eV

29. The total number of orbitals in the principal shell of He+ that has energy equal to hcR/4, is (R = Rydberg constant)
A) 4 B) 16 C) 9 D) none of these

30. Which of the following species contain unpaired electron(s)?
A) CN– B) CN+ C) NO+ D) none

31. Which of the following anions will be the weakest base?
A) C6H5 – SO3 – B) C6H5 – O – C) C6H5 – CO2 – D) C2H5 – O –

32. The complex ion which has no ‘d’ electrons in the central metal atom is
A) MnO4 – B) [CO(NH3)6]3+ C) [Fe(CN)6]3– D) [Cr(H2O)6]3+

33. The ratio of de Broglie wavelength of molecules of H2 and He at 27o C and 127o C respectively is
A) 1.633 B) 0.612 C) 1.265 D) 0.79

34. Equal masses of methane and oxygen are mixed in an empty container at 25o C. The fraction of the total pressure exerted by oxygen is

35. To neutralize completely 20mL of 0.1 M aqueous solution of phosphorous acid, the volume of 0.1 M aqueous KOH solution required is
A) 60mL B) 20mL C) 40mL D) 10mLAjay Tripathi
Which species contain unpair Which species contain unpaired electr ed electron(s)? on(s)?


1)B 2)C 3)C 4)D 5)C 6)A 7)D 8)D 9)B 10)C 11)D 12)D 13)D 14)D 15)C 16)B 17)B 18)C 19)C 20)B 21)C 22)C 23)D 24)B 25)C 26)B 27)D 28)D 29)B 30)D 31)A 32)A 33)A 34)D 35)C.

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