Practice Questions

Q25.Orange light of wavelength 6000 × 10–10 m illuminates a single slit of width 0. 6 × 10–4 m. The maximum possible number of diffraction minima produced on both sides of the central maximum is __________

Q25.A part of a complete circuit is shown in the figure. At some instant, the value of current I is 1A and it is decreasing at a rate of 102 As−1 . The value of the potential difference Vp −VQ, (in volts) at that instant is-

Q25.When an object is kept at a distance of 30 cm from a concave mirror, the image is formed at a distance of 10 cm from the mirror. If the object is moved with a speed of 9 cm s−1 , the speed (in cm s−1 ) with which image moves at that instant is

Q25.An observer can see through a small hole on the side of a jar (radius 15 cm ) at a point at height of 15 cm from the bottom (see figure). The hole is at a height of 45 cm. When the jar is filled with a liquid up to a height of 30 cm the same observer can see the edge at the bottom of the jar. If the refractive index of the liquid is N , where N is an integer, the value of N is 100 JEE Main 2020 (03 Sep Shift 1) JEE Main Previous Year Paper

Q26.The ammonia (NH3) released on quantitative reaction of 0.6 g urea (NH2CONH2) with sodium hydroxide (NaOH) can be neutralized by (1) 200 ml of 0.4 NHCl (2) 200 ml of 0.2 NHCl (3) 100 ml of 0.2 NHCl (4) 100 ml of 0.1 NHCl

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.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 strengths of 5. 6 volume hydrogen peroxide (of density 1 g/ mL ) in terms of mass percentage and molarity (M) respectively, are: (Take molar mass of hydrogen peroxide as 34 g/ mol) (1) 1.7 and 0.5 (2) 0.85 and 0.25 (3) 1.7 and 0.25 (4) 0.85 and 0.5

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 figure that is not a direct manifestation of the quantum nature of atom is : (1) (2) (3) (4)

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.The correct statement about probability density (except at infinite distance from nucleus) is : (1) It can be zero for 1s orbital (2) It can be negative for 2p orbital (3) It can be zero for 3p orbital (4) It can never be zero for 2s orbital

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.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.

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.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.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.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.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.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.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

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

Q28.Arrange the following bonds according to their average bond energies in descending order: C −Cl, C −Br, C −F, C −I (1) C −F > C −Cl > C −Br > C −I (2) C −Br > C −I > C −Cl > C −F (3) C −I > C −Br > C −Cl > C −F (4) C −Cl > C −Br > C −I > C −F