Practice Questions

Q50.The number of Cl = O bonds in perchloric acid is, ′′… … … . . .′′ β3 8 α3 8 is :

Q50.The number of chiral carbon(s) present in peptide, lle-Arg-Pro, is ................

Q50. The number of groups present in a tripeptide Asp – Glu – Lys is ____

Q50.For the disproportionation reaction 2 Cu+(aq) ⇌Cu(s) + Cu2+(aq) at 298K,ln K (where K is the equilibrium constant) is _______ ×10−1 Given : (E°Cu2+ / Cu+= 0. 16V E°Cu+ / Cu= 0. 52V RTF = 0. 025)

Q50.The mass percentage of nitrogen in histamine is ________

Q50.Complexes (ML5) of metals Ni and Fe have ideal square pyramidal and trigonal bipyramidal geometries, respectively. The sum of the 90o, 120o and 180o L −M −L angles in the two complexes is_______

Q50.Consider the following reactions A (i)CH3MBr B 573KCu 2 −methyl −2 −butene . The mass percentage of (ii)H3O+ carbon in A is _____________.

Q50.The number of chiral centres present in threonine is _________

Q50.The number of chiral carbons in chloramphenicol is ____________.

Q50.The number of chiral centres in penicillin is _________.

Q50.The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are x, y and z. Then sum of x, y and z is ........... Na4[Fe (CN)5(NOS)] Na4[FeO4] [Fe2 (CO)9] (A) (B) (C)

Q50.The number of chiral centres present in [B] is _____

Q50.A solution of phenol in chloroform when treated with aqueous NaOH gives compound Pas a major product. The mass percentage of carbon in P is ______ .

Q50.The number of sp2 hybridised carbons present in “Aspartame” is

Q51.Let α and β be the roots of the equation x2 −x −1 = 0 . If pk = (α)k + (β)k, k ≥1, then which one of the following statements is not true? (1) p3 = p5 −p4 (2) p5 = 11 (3) (p1 + p2 + p3 + p4 + p5) = 26 (4) p5 = p2 ⋅p3

Q31.A 10mg effervescent tablet containing sodium bicarbonate and oxalic acid releases 0.25 mL of CO2 at T = 298.15 K and P = 1 bar. If molar volume of CO2 is 25.0 L under such condition, what is the percentage of sodium bicarbonate in each tablet? [Molar mass of NaHCO3 = 84 g mol−1] (1) 0.84 (2) 33.6 (3) 16.8 (4) 8.4

Q32.If the de Broglie wavelength of the electron in nth Bohr orbit in a hydrogenic atom is equal to 1.5πa0 (a0 is Bohr radius ), then the value of nz is: (1) 1.50 (2) 1.0 (3) 0.4 (4) 0.75

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

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.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

Q36.In order to oxidize a mixture of one mole of each of FeC2O4, Fe2 ( C2O4 ) 3, FeSO4 and Fe2 ( SO4 ) 3 in acidic medium, the number of moles of KMnO4 is: (1) 1 (2) 2 (3) 3 (4) 1.5

Q36.In the reaction of oxalate with permanganate in acidic medium, the number of electrons involved in producing one molecule of CO2 is: (1) 2 (2) 10 (3) 1 (4) 5

Q36.The molar solubility of Cd(OH)2 is 1.84 × 10−5M in water. The expectes solunility of Cd(OH)2 in a buffer solution of pH = 12 is: (1) 2.49 × 10−10M (2) 2.491.84 × 10−9M (3) 1.84 × 10−9M (4) 6.23 × 10−11M

Q36.An open vessel at 27oC is heated until two fifth of the air (assumed as an ideal gas) in it has escaped from the vessel. Assuming that the volume of the vessel remains constant, the temperature to which the vessel has heated is: (1) 750oC (2) 500oC (3) 750K (4) 500K

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