Practice Questions

Q34.For silver, Cp (JK-1mol-1 ) = 23 + 0.01T . If the temperature T of 3 moles of silver is raised from 300 K to 1000 K at 1 atm pressure, the value of ΔH will be close to: JEE Main 2019 (08 Apr Shift 1) JEE Main Previous Year Paper (1) 16 kJ (2) 62 kJ (3) 13 kJ (4) 21 kJ

Q34.Points I, II and III in the following plot respectively correspond to (Vmp: most probable velocity) (1) Vmp of N2300 K; Vmp of H2300 K; Vmp of (2) Vmp of H2300 K; Vmp of N2300 K; Vmp of O2400 K; O2400 K; (3) Vmp of N2300 K; Vmp of O2400 K; Vmp of (4) Vmp of O2400 K; Vmp of N2300 K; Vmp of H2300 K; H2300 K;

Q34.Two blocks of the same metal having same mass and at temperature T1, and T2 , respectively, are brought in contact with each other and allowed to attain thermal equilibrium at constant pressure. The change in entropy, JEE Main 2019 (11 Jan Shift 1) JEE Main Previous Year Paper ΔS, for this process is : 2 (T1+T2) (1) CP ln T1T2 [ (T1+T2)24 T1 T2 ] (2) 2Cp ln [ 1 ] 2CP ln [ 2T1+T2T1 T2 ] (3) 2CP ln ( 4T1+T2T1 T2 ) (4)

Q34.According to molecular orbital theory, which of the following is true with respect to Li2+ and Li2- ? (1) 𝐿𝑖2+ is stable and 𝐿𝑖2- is unstable (2) Both are unstable (3) Both are stable (4) 𝐿𝑖2+ is unstable and 𝐿𝑖2- is stable Q35.0.5 moles of gas A and x moles of gas B exert a pressure of 200 Pa in a container of volume 10 m3 at 1000 K . Given, R is the gas constant in JK-1mol-1, x is: (1) 4 + R (2) 2R 2R 4 + R 4 - R 2R (3) (4) 2R 4 - R

Q34.The correct order of atomic radii is: (1) Ce>Eu>Ho>N (2) N>Ce>Eu>Ho (3) Ho>N>Eu>Ce (4) Eu>Ce>Ho>N

Q34.The volume of gas A is twice than that of gas B . The compressibility factor of gas A is thrice than that of gas B at same temperature. What are the pressures of the gases for equal number of moles? (1) 2PA = 3PB (2) PA = 2PB (3) 3PA = 2PB (4) PA = 3PB

Q34.In which of the following processes, the bond order has increased and paramagnetic character has changed to diamagnetic? (1) O2 →O+2 (2) NO →NO+ (3) O2 →O−2 (4) N2 →N 2+

Q35.An ideal gas is allowed to expand from 1 L to 10 L against a constant external pressure of 1 bar. The work done in kJ is: (1) +10.0 (2) -2.0 (3) -0.9 (4) -9.0

Q35.What are the values of Kp for the following reactions at 300 K respectively? Kc (At 300 K, RT = 24 .62 dm2 atm mol−1 ) N2 (g) + O2 (g) ⇌2 NO (g) N2O4 (g) ⇌2 NO (g) N2 (g) + 3H2 (g) ⇌2 NH3 (g) (1) 24 .63 dm3 atm mol−1, (2) 1 ,24.62 dm6 atm3 mol−1 606 .0 dm6 atm2 mol−2, 606 .0 dm6 atm2 mol−2 1 .65 ×10−3 dm−6 atm−2 mol2 (3) 1 ,24.62 dm3 atm mol−1 (4) 1 , 4.1 ×10−2 dm−3 atm−1 mol, 1 .65 ×10−3 dm−6 atm−2 mol2 606 dm6 atm2 mol−2 JEE Main 2019 (10 Jan Shift 1) JEE Main Previous Year Paper

Q35.The entropy change associated with the conversion of 1 kg of ice at 273 K to water vapours at 383 K is: (Specific heat of water liquid and water vapour are 4.2 kJ K − and 2.0 kJ K −1kg−1 ; heat of liquid fusion and vaporization of water are 334 kJ kg−1 and 2491 kJ kg−1 , respectively). ( log 273 = 2.436, log 373 = 2.572, log 383 = 2.583 ) (1) 9.26 kJ kg−1K −1 (2) 2.64 kJ kg−1K −1 (3) 8.49 kJ kg−1K −1 (4) 7.90 kJ kg−1K −1

Q35.During compression of a spring the work done is 10 kJ and 2 kJ escaped to the surroundings as heat. The change in internal energy, ΔU(in kJ) is: (1) −8 (2) 8 (3) 12 (4) −12

Q35.The standard reaction Gibbs energy for a chemical reaction at an absolute temperature T is given by ΔG∘= A −BT where A and B are non-zero constants. Which of the following is true about this reaction? (1) Exothermic if B < 0 (2) Endothermic if A > 0 (3) Endothermic if A < 0 and B > 0 (4) Exothermic if A > 0 and B < 0

Q35.In which one of the following equilibria, Kp ≠Kc? (1) 2HI(g) ⇌H2(g) + I2(g) (2) 2C(s) + O2(g) ⇌2CO(g) (3) 2NO(g) ⇌N2(g) + O2(g) (4) NO2(g) + SO2(g) ⇌NO(g) + SO3(g)

Q35.Consider the van der Waal's constants, a and b, for the following gases. Gas Ar Ne Kr Xe a/(atm dm6 mol−2) 1.3 0.2 5.1 4.1 b/(10−2 dm3 mol−1) 3.2 1.7 1.0 5.0 Which gas is expected to have the highest critical temperature? (1) Kr (2) Ar (3) Xe (4) Ne

Q35.If solubility product of Zr3 ( PO4 ) 4 is denoted by Ksp and its molar solubility is denoted by S , then which of the following relation between S and Ksp is correct? (1) Ksp 16 (2) Ksp 17 (3) Ksp 19 (4) Ksp 17 S = S = S = S = 144 6912 929 216

Q35.For the chemical reaction X ⇌Y, the standard reaction Gibbs energy depends on temperature T (in K ) as ΔrG∘( in kJmol−1) = 120 −38 T The major component of the reaction mixture at T is : (1) Y if T = 300K (2) Y if T = 280 K (3) X if T = 350 K (4) X if T = 315K

Q35.Among the following molecules/ ions, C22 - , N22 - , O22 - , O2 Which one is diamagnetic and has the shortest bond length? (1) N22 - (2) O22 - (3) O2 (4) C22 - Q36.5 moles of an ideal gas at 100 K are allowed to undergo reversible compression till its temperature becomes 200 K . If CV = 28 J K-1, calculate ∆U and ∆pV for the process. (R = 8.0 J K-1 mol-1 ) (1) ∆U = 14 J; ∆pV = 0.8 J (2) ∆U = 14 kJ; ∆pV = 18 kJ (3) ∆U = 14 kJ; ∆pV = 4 kJ (4) ∆U = 2.8 kJ; ∆pV = 0.8 kJ

Q35.The element that shows greater ability to form pπ −pπ multiple bonds is: (1) Sn (2) C (3) Si (4) Ge

Q35.For a diatomic ideal gas in a closed system, which of the following plots does not correctly describe the relation between various thermodynamic quantities? (1) (2) (3) (4) JEE Main 2019 (12 Jan Shift 1) JEE Main Previous Year Paper

Q35.The difference between ∆H and ∆U is ∆H - ∆U, when the combustion of one mole of heptane l is carried out at a temperature T , is equal to: (1) -4RT (2) 3RT (3) 4RT (4) -3RT

Q35.Consider the following table: Gas a/(k Pa dm6mol−1) b/(dm3mol−1) A 642.32 0.05196 B 155.21 0.04136 JEE Main 2019 (10 Apr Shift 1) JEE Main Previous Year Paper Gas a/(k Pa dm6mol−1) b/(dm3mol−1) C 431.91 0.05196 D 155.21 0.4382 a and b are vander Waals constants. The correct statement about the gases is: (1) Gas C will occupy more volume than gas A ; gas (2) Gas C will occupy lesser volume than gas A ; gas B will be lesser compressible than gas D B will be lesser compressible than gas D (3) Gas C will occupy more volume than gas A ; gas (4) Gas C will occupy lesser volume than gas A ; gas B will be more compressible than gas D B will be more compressible than gas D

Q36.Enthalpy of sublimation of iodine is 24 cal g-1 at 200°C . If specific heat of I2 (s) and I2 (vap) are 0.055 and 0.031 cal g-1K-1 respectively, then enthalpy of sublimation of iodine at 250°C in cal g-1 is: (1) 11.4 (2) 2.85 (3) 22.8 (4) 5.7

Q36.A mixture of 100 m mol of Ca (OH)2 and 2 g of sodium sulphate was dissolved in water and the volume was made up to 100 mL. What is the mass of calcium sulphate formed and the concentration of OH− in resulting solution, respectively? (Molar mass of Ca (OH)2, Na2 SO4 and CaSO4 are 74, 143 and 136 g mol−1, respectively; Ksp of Ca (OH)2 is 5 .5 ×10−6 ) (1) 1 .9 g, 0 .14 mol L−1 (2) 13 .6 g, 0 .28 mol L−1 (3) 1 .9 g, 0 .28 mol L−1 (4) 13 .6 g, 0 .14 mol L−1

Q36.The temporary hardness of water is due to: (1) Na2 SO4 (2) NaCl (3) CaCl2 (4) Ca (HCO3)2

Q36.For the reaction, 2SO2g + O2g ⇌2SO3g, ∆H = - 57.2 kJ mol-1 and Kc = 1.7 × 1016 . Which of the following statements is incorrect? (1) The equilibrium constant is large suggestive of (2) The equilibrium will shift in forward direction as reaction going to completion and so, no catalyst the pressure increases. is required. (3) The equilibrium constant decreases as the (4) The addition of inert gas at constant volume will temperature increases. not affect the equilibrium constant.