Practice Questions

Q26.Amongst the following statements, that which was not proposed by Dalton was : (1) chemical reactions involve reorganization of (2) all the atoms of a given element have identical atoms. These are neither created nor destroyed in properties including identical mass. Atoms of a chemical reaction. different elements differ in mass. (3) when gases combine or reproduced in a chemical (4) matter consists of indivisible atoms. reaction they do so in a simple ratio by volume provided all gases are at the same T & P.

Q26.The shortest wavelength of H atom in the Lyman series is λ1 . The longest wavelength in the Balmer series of He+ is : (1) 36λ1 (2) 5λ1 5 9 (3) 9λ1 (4) 27λ1 5 5

Q26.A solution of two components containing n1 moles of the 1st component and n2 moles of the 2nd component is prepared. M1 and M2 are the molecular weights of component 1 and 2 respectively. If d is the density of the solution in gmI−1, C2 is the molarity and x2 is the mole fraction of the 2nd component, then C2 can be expressed as : (1) C2 = 1000x2 (2) C2 = dx2 M1+x2(M2−M1) M1+x2(M2−M1) (3) C2 = 1000 dx2 (4) C2 = dx1 M1+x2(M2−M1) M2+x2(M2−M1)

Q26.The difference between the radii of 3rd and 4th orbits of L2+i is ΔR1 . The difference between the radii of 3rd and 4th orbits of He+ ΔR2. Ratio ΔR1 : ΔR2 is : (1) 8 : 3 (2) 3 : 8 (3) 2 : 3 (4) 3 : 2

Q26.For the Balmer series, in the spectrum of H atom, −v = RH{ n211 2 }, the correct statements among (IV) are, (I) As wavelength decreases, the lines in the series converge. (II) The integer n1 is equal to 2 / (III) The lines of the longest wavelength correspond to n2 = 3 . (IV) The ionization energy of hydrogen can be calculated from the wave number of these lines. (1) (I), (III), (IV) (2) (I), (II), (III) (3) (I), (II), (IV) (4) (II), (III), (IV)

Q26.The first and second ionisation enthalpies of a metal are 496 and 4560 kJ mol−1 , respectively. How many moles of HCl and H2SO4, respectively, will be needed to react completely with 1 mole of the metal hydroxide? (1) 1 and 1 (2) 2 and 0.5 (3) 1 and 2 (4) 1 and 0.5

Q26.The region in the electromagnetic spectrum where the Balmer series lines appear is: (1) Visible (2) Microwave (3) Infrared (4) Ultraviolet

Q26.The average molar mass of chlorine is 35. 5 g mol−1 . The ratio of 35Cl to 37Cl in naturally occurring chlorine is close to : (1) 4 : 1 (2) 3 : 1 (3) 2 : 1 (4) 1 : 1

Q26.Preparation of Bakelite proceeds via reactions: (1) Electrophilic addition and dehydration (2) Condensation and elimination (3) Electrophilic substitution and dehydration (4) Nucleophilic addition and dehydration

Q27.Within each pair of elements F and Cl , S and Se , and Li and Na , respectively, the elements that release more energy upon an electron gain are (1) Cl, Se and Na (2) Cl, S and Li (3) F, S and Li (4) F, Se and Na

Q27. B has a smaller first ionization enthalpy than Be. Consider the following statement: (I) it is easier to remove 2p electron than 2s electron (II) 2p electron of B is more shielded from the nucleus by the inner core of electrons than the 2s electrons of Be (III) 2s electron has more penetration power than 2p electron (IV) atomic radius of B is more than Be (atomic number B : 5, Be = 4 ) The correct statements are. (1) (I), (II) and (IV) (2) (II), (III) and (IV) (3) (I), (II) and (III) (4) (I), (III) and (IV)

Q27.Consider the hypothetical situation where the azimuthal quantum number, 𝓁 , takes values 0, 1, 2, … … . . n + 1. Where n is the principal quantum number. Then, the element with atomic number: (1) 9 is the first alkali metal (2) 13 has a half-filled valence subshell (3) 8 is the first noble gas (4) 6 has a 2p-valence subshell JEE Main 2020 (03 Sep Shift 2) JEE Main Previous Year Paper

Q27.In general, the property (magnitudes only) that shows an opposite trend in comparison to other properties across a period is : (1) lonization enthalpy (2) Electronegativity (3) Electron gain enthalpy (4) Atomic radius

Q27.The number of orbitals associated with quantum numbers n = 5, ms = + 21 is: (1) 11 (2) 25 (3) 50 (4) 15

Q27.A mixture of gases O2, H2 and CO are taken in a closed vessel containing charcoal The graph that represents the correct behaviour of pressure with time is: (1) (2) (3) (4) JEE Main 2020 (09 Jan Shift 2) JEE Main Previous Year Paper

Q27.The correct order of the ionic radii of O2−, N3−, F−, Mg2+, Na+ and Al3+ is : (1) N3−< O2−< F−< Na+ < Mg2* < AI3+ (2) AI3+ < Na+ < Mg2+ < O2−< F−< N3− (3) Al3+ < Mg2+ < Na+ < F−< O2−< N3− (4) N3−< F−< O2−< Mg2+ < Na+ < AI3+

Q27.The first ionization energy (in kJ/mol ) of Na, Mg, Al and Si respectively are: (1) 496, 737, 577, 786 (2) 496, 577, 737, 786 (3) 786, 737, 577, 496 (4) 496, 577, 786, 737

Q27.The process that is NOT endothermic in nature is : (1) Ar(g) + e−→Ar−(g) (2) H(g) + e−→H−(g) (3) O− + e−→O2− (g) (g) (4) Na(g) →Na+(g) + e−

Q27.The elements with atomic numbers 101 and 104 belong to, respectively: (1) Group 11 and Group 4 (2) Actinoids and Group 6 (3) Actinoids and Group 4 (4) Group 6 and Actinoids

Q27.The increasing order of the atomic radii of the following elements is: (a)C (b)O (c)F (d)Cl (e)Br (1) (b) < (c) < (d) < (a) < (e) (2) (d) < (c) < (b) < (a) < (e) (3) (c) < (b) < (a) < (d) < (e) (4) (a) < (b) < (c) < (d) < (e)

Q27.Three elements X, Y and Z are in the 3rd period of the periodic table. The oxides of X, Y and Z , respectively, are basic, amphoteric and acidic. The correct order of the atomic numbers of X, Y and Z is: (1) Z < Y < X (2) X < Y < Z (3) X < Z < Y (4) Y < X < Z

Q27.For a reaction 4 M(s) + nO2(g) →2M2On(s) The free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which : (1) the slope change from negative to positive (2) the free energy change show a change from negative to positive value (3) the slope changes from positive to negative (4) the slope changes from positive to zero

Q27.The variation of equilibrium constant with temperature is given below : Temperature EquilibriumConstant T1 = 25°C K1 = 10 T2 = 100°C K2 = 100 JEE Main 2020 (06 Sep Shift 1) JEE Main Previous Year Paper The values of ΔH°, ΔG° at T1 and ΔG° at T2 (in kJ mol−1 ) respectively, are close to [use R = 8. 314 JK−1 mol−1 ] (1) 28. 4, −7. 14 and −5. 71 (2) 0. 64, −7. 14 and −5. 71 (3) 28. 4, −5. 71 and −14. 29 (4) 0. 64, −5. 71 and −14. 29

Q27.In the sixth period, the orbitals that are filled are : (1) 6s, 4f, 5d, 6p (2) 6s, 5d, 5f, 6p (3) 6s, 5f, 6d, 6p (4) 6s, 6p, 6d, 6f

Q27.If the boiling point of H2O is 373 K, and the boiling point of H2S will be : (1) less than 300 K (2) equal to 373 K (3) more than 373 K (4) greater than 300 K but less than 373 K