Practice Questions

Q30.The wavelength of an X-ray beam is 10 Å . The mass of a fictitious particle having the same energy as that of the X-ray photons is x h kg. The value of x is ___ . ( h =Planck's constant) 3

Q30.A signal of 0. 1 kW is transmitted in a cable. The attenuation of cable is −5 dB per km and cable length is 20 km. The power received at the receiver is 10−x W. The value of x is _________. [Gain in dB = 10 log10( POPi )]

Q31.An inorganic Compound ′X′ on treatment with concentrated H2 SO4 produces brown fumes and gives dark brown ring with FeSO4 in presence of concentrated H2 SO4 . Also Compound ′X′ gives precipitate ′Y′, when its solution in dilute HCl is treated with H2S gas. The precipitate ′Y′ on treatment with concentrated HNO3 followed by excess of NH4 OH further gives deep blue coloured solution, Compound ′X′ is: (1) Co (NO3)2 (2) Pb (NO2)2 (3) Cu (NO3)2 (4) Pb (NO3)2

Q31.Consider the elements Mg, Al, S, P and Si, the correct increasing order of their first ionisation enthalpy is: (1) Al < Mg < Si < S < P (2) Al < Mg < S < Si < P (3) Mg < Al < Si < P < S (4) Mg < Al < Si < S < P

Q31.Identify the elements X and Y using the ionization energy values given below : Ionization energy (kJ / mol) 1st 2nd X 495 4563 Y 731 1450 (1) X = Na; Y = Mg (2) X = Mg; Y = F (3) X = Mg; Y = Na (4) X = F; Y = Mg

Q31.Given below are two statements : Statement I : Rutherford's gold foil experiment cannot explain the line spectrum of hydrogen atom. Statement II : Bohr's model of hydrogen atom contradicts Heisenberg's uncertainty principle. In the light of the above statements, choose the most appropriate answer from the options given below: (1) Statement I is false but statement II is true. (2) Statement I is true but statement II is false. (3) Both statement I and statement II are false. (4) Both statement I and statement II are true.

Q31.Outermost electronic configuration of a group 13 element, E, is 4 s2, 4p1. The electronic configuration of an element of p-block period-five placed diagonally to element, E is: (1) [Kr]3 d104 s24p2 (2) [Ar]3 d104 s24p2 (3) [Xe]5 d106 s26p2 (4) [Kr]4 d105 s25p2

Q31.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R : Assertion A : The H −O −H bond angle in water molecule is 104. 5°. Reason R : The lone pair − lone pair repulsion of electrons is higher than the bond pair − bond pair repulsion. (1) A is false but R is true (2) Both A and R are true, but R is not the correct explanation of A (3) A is true but R is false (4) Both A and R are true, and R is the correct explanation of A

Q31.Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Metallic character decreases and non-metallic character increases on moving from left to right in a period. Reason (R): It is due to increase in ionisation enthalpy and decrease in electron gain enthalpy, when one moves JEE Main 2021 (31 Aug Shift 1) JEE Main Previous Year Paper from left to right in a period. In the light of the above statements, choose the most appropriate answer from the options given below : (1) (A) is false but (R) is true. (2) Both (A) and (R) are correct and (R) is the correct explanation of (A) (3) Both (A) and (R) are correct but (R) is not the correct explanation of (A). (4) (A) is true but (R) is false.

Q31.Which among the following species has unequal bond lengths? (1) SiF4 (2) SF4 (3) XeF4 (4) BF4

Q31.According to Bohr's atomic theory: (A) Kinetic energy of electron is ∝Z2 . n2 (B) The product of velocity (v) of electron and principal quantum number (n), ′vn′∝Z2. (C) Frequency of revolution of electron in an orbit is ∝Z3 . n3 (D) Coulombic force of attraction on the electron is ∝Z3 . n4 Choose the most appropriate answer from the options given below: (1) (A), (C) and (D) only (2) (A) and (D) only (3) (C) only (4) (A) only

Q31.Given below are two statements: Statement I : Bohr's theory accounts for the stability and line spectrum of Li+ ion. Statement II : Bohr's theory was unable to explain the splitting of spectral lines in the presence of a magnetic field. In the light of the above statements, choose the most appropriate answer from the options given below: (1) Both statement I and statement II are true. (2) Statement I is false but statement II is true. (3) Both statement I and statement II are false. (4) Statement I is true but statement II is false. JEE Main 2021 (18 Mar Shift 2) JEE Main Previous Year Paper

Q31.Number of paramagnetic oxides among the following given oxides is ___________ . Li2O, CaO, Na2O2, KO2, MgO and K2O (1) 1 (2) 3 (3) 0 (4) 2

Q31.The correct order of ionic radii for the ions, P3−, S2−, Ca2+, K+, Cl− is : (1) P3−> S2−> Cl−> K+ > Ca2+ (2) P3−> S2−> Cl−> Ca2+ > K+ (3) Cl−> S2−> P3−> Ca2+ > K+ (4) K+ > Ca2+ > P3−> S2−> Cl−

Q31.The spin only magnetic moments (in BM) for free Ti3+, V2+ and Sc3+ ions respectively are (At.No. Sc : 21, Ti : 22, V : 23 ) (1) 3. 87, 1. 73, 0 (2) 1. 73, 3. 87, 0 (3) 1. 73, 0, 3. 87 (4) 0, 3. 87, 1. 73

Q31.Given below are two statements : Statement I : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in positive charges on the nucleus as there is no strong hold on the electron by the nucleus. Statement II : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in principle quantum number. In the light of the above statements, choose the most appropriate answer from the options given below: (1) Statement I is false but Statement II is true (2) Statement I is true but Statement II is false (3) Both Statement I and Statement II are false (4) Both Statement I and Statement II are true

Q31.The incorrect expression among the following is : ΔH° - TΔS° (1) For isothermal process (2) lnK = RT Vf wreversible = - nRT ln Vi ΔGSystem / RT (3) = - T (at constant P) (4) K = e-ΔG° ΔSTotal

Q32.During which of the following processes, does entropy decrease ? (A) Freezing of water to ice at 0°C (B) Freezing of water to ice at −10°C (C) N2( g) + 3H2( g) →2 NH3( g) (D) Adsorption of CO(g) and lead surface (E) Dissolution of NaCl in water (1) (A), (B),(C) and (D) only (2) (B) and (C) only (3) (A) and (E) only (4) (A), (C) and (E) only

Q32.Which pair of oxides is acidic in nature? (1) B2O3, CaO (2) N2O, BaO (3) CaO, SiO2 (4) B2O3, SiO2

Q32.In polythionic acid, H2 SxO6(x = 3 to 5) the oxidation state(s) of sulphur is/are: (1) +6 only (2) +5 only (3) 0 and +5 only (4) +3 and +5 only

Q32.Match List- I with List- II. List- I List- II Electronic configuration of elements ΔiH in kJ mol−1 (a) 1s22s2 (p) 801 (b) 1s22s22p4 (q) 899 (c) 1s22s22p3 (r) 1314 (d) 1s22s22p1 (s) 1402 Choose the most appropriate answer from the options given below: (1) (a) →(q), (b) →(r), (c) →(s), (d) →(p) (2) (a) →(p), (b) →(r), (c) →(s), (d) →(q) (3) (a) →(p), (b) →(s), (c) →(r), (d) →(q) (4) (a) →(s), (b) →(p), (c) →(q), (d) →(r)

Q32.The CORRECT order of first ionisation enthalpy is: (1) Mg < S < Al < P (2) Mg < Al < S < P (3) Al < Mg < S < P (4) Mg < Al < P < S

Q32.The first ionization energy of magnesium is smaller, as compared to that of elements X and Y , but higher than that of Z. The elements X, Y and Z , respectively, are : (1) chlorine, lithium and sodium (2) argon, lithium and sodium (3) argon, chlorine and sodium (4) neon, sodium and chlorine

Q32.The plots of radial distribution functions for various orbitals of hydrogen atom against ' r′ are given below. The correct plot for 3s orbital is : (1) (2) (3) (4)

Q32.Match List-I with List-II List - I List - II (Elements) (Properties) (a) SF4 (i) sp3 d2 (b) IF5 (ii) d2 sp3 (c) NO+2 (iii) sp3 d (d) NH+4 (iv) sp3 (v) sp Choose the correct answer from the options given below: (1) (a)-(i), (b)-( ii), (c)-(v) and (d)-(iii) (2) (a)-(ii), (b)-(i), (c)-(iv) and (d)-(v) (3) (a)-(iii), (b)-(i), (c)-(v) and (d)-(iv) (4) (a)-(iv), (b)-(iii), (c)-(ii) and (d)-(v)