Practice Questions

Q35.In a Young's double slit experiment the intensity at a point where the path difference is λ ( λ being the 6 wavelength of the light used) is I. If I0 denotes the maximum intensity, I0I is equal to (1) 1 (2) √3 √2 2 (3) 1/2 (4) 3/4

Q36.Photon of frequency v has a momentum associated with it. If c is the velocity of light, the momentum is JEE Main 2007 JEE Main Previous Year Paper (1) v/c (2) hvc (3) hv/c2 (4) hv/c

Q37.Which of the following transitions in hydrogen atoms emit photons of highest frequency? (1) n = 2 to n = 6 (2) n = 6 to n = 2 (3) n = 2 to n = 1 (4) n = 1 to n = 2

Q38.If Mo is the mass of an oxygen isotope 8O17, Mp and MN are the masses of a proton and a neutron respectively, the nuclear binding energy of the isotope is (1) (Mo −8Mp)C2 (2) (Mo −8Mp −9MN)C2 (3) MoC2 (4) (Mo −17MN)C2

Q39.In gamma ray emission from a nucleus (1) both the neutron number and the proton number (2) there is no change in the proton number and the change neutron number. (3) only the neutron number changes (4) only the proton number changes

Q40.The half-life period of a radio-active element X is same as the mean life time of another radioactive element Y . Initially they have the same number of atoms. Then (1) X will decay faster than Y (2) Y will decay faster than X (3) X and Y have same decay rate initially (4) X and Y decay at same rate always.

Q41. If in a p −n junction diode, a square input signal of 10 V is applied as shown Then the output signal across RL will be (1) (2) (3) (4)

Q42.Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate? JEE Main 2007 JEE Main Previous Year Paper (1) The number of free conduction electrons is (2) The number of free conduction electrons is significant in C but small in Si and Ge. negligible small in all the three. (3) The number of free electrons for conduction is (4) The number of free electrons for conduction is significant in all the three. significant only in Si and Ge but small in C.

Q43.The density (in g mL−1 ) of a 3.60 M sulphuric acid solution that is 29% H2SO4 (Molar mass = 98 g mol−1 ) by mass will be (1) 1.64 (2) 1.88 (3) 1.22 (4) 1.45

Q44.Which of the following sets of quantum numbers represents the highest energy of an atom? (1) n = 3, l = 2, m = 1, s = +1/2 (2) n = 3, l = 2, m = 1, s = +1/2 (3) n = 4, l = 0, m = 0, s = +1/2 (4) n = 3, l = 0, m = 0, s = +1/2

Q45.The stability of dihalides of Si, Ge, Sn and Pb increases steadily in the sequence (1) GeX2 ≪SiX2 ≪SnX2 ≪PbX2 (2) SiX2 ≪GeX2 ≪PbX2 ≪SnX2 (3) SiX2 ≪GeX2 ≪SnX2 ≪PbX2 (4) PbX2 ≪SnX2 ≪GeX2 ≪SiX2

Q46.In which of the following ionization processes, the bond order has increased and the magnetic behaviour has changed? (1) C2 ⟶C+2 (2) NO ⟶NO+ (3) O2 ⟶O+2 (4) N2 ⟶N+2

Q47.Which of the following hydrogen bonds is the strongest? (1) O −H … … N (2) F −H … … F (3) O −H … … . O (4) O −H … … F

Q48.Which of the following species exhibits the diamagnetic behaviour? (1) O2−2 (2) O+2 (3) O2 (4) NO

Q49.The charge/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizinig order of the polarizing power of the cationic species, K+, Ca2+, Mg2+, Be2+ ? (1) Mg2+, Be2+, K+, Ca2+ (2) Be2+, K+, Ca2+, Mg2+ (3) K+, Ca2+, Mg2+, Be2+ (4) Ca2+, Mg2+, Be2+, K+

Q50.Equal masses of methane and oxygen are mixed in an empty container at 25∘C . The fraction of the total pressure exerted by oxygen is (1) 2 (2) 1 3 3 × 298273 (3) 1 (4) 1 3 2

Q51.A 5.25% solution of a substance is isotonic with a 1.5% solution of urea ( molar mass = 60 g mol−1 ) in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 g cm−3 , molar mass of the substance will be JEE Main 2007 JEE Main Previous Year Paper (1) 90.0 g mol−1 (2) 115.0 g mol−1 (3) 105.0 g mol−1 (4) 210.0 g mol−1

Q52.In the reaction. 2Al(s) + 6HCl(s) ⟶2Al3+(aq) + 6Cl−(aq) + 3H2(g), (1) 6 L HCl(aq) is consumed for every 3 L H2(g) (2) 33.6 L H2(g) is produced regardless of produced temperature and pressure for every mole Al that reacts (3) 67.2 L H2(g) at STP is produced for every mole (4) 11.2 H2(g) at STP is produced for every mole Al that reacts HCl(aq) consumed

Q53.Assuming that water vapour is an ideal gas, the internal energy (ΔU) when 1 mol of water is vapourised at 1 bar pressure and 100∘C, (Given: Molar enthalpy of vapourization of water at 1 bar and 373 K = 41 kJ mol−1 and R = 8.3 J mol−1 K−1 ) will be (1) 4.100 kJ mol−1 (2) 3.7904 kJ mol−1 (3) 37.904 kJ mol−1 (4) 41.00 kJ mol−1

Q54.Identify the correct statement regarding a spontaneous process (1) For a spontaneous process in an isolated system, (2) Endothermic processes are never spontaneous the change in entropy is positive (3) Exothermic processes are always spontaneous (4) Lowering of energy in the reaction process is the only criterion for spontaneity

Q55.In conversion of lime-stone to lime, CaCO3( s) ⟶CaO(s) + CO2( g) the vales of ΔH∘ and ΔS∘ are +179.1 kJ mol−1 and 160.2 J/K respectively at 298 K and 1 bar. Assuming that ΔH∘ do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is (1) 1008 K (2) 1200 (3) 845 K (4) 1118 K

Q56.The pKa of a weak acid (HA) is 4.5 . The pOH of an aqueous buffered solution of HA in which 50% of the acid is ionized is (1) 4.5 (2) 2.5 (3) 9.5 (4) 7.0

Q57.In a sautrated solution of the sparingly soluble strong electrolyte AgIO3 (Molecular mass = 283 ) the equilibrium which sets in is AgIO3(s) ⇌Ag+(aq) + IO−3(aq) If the solubility product constant Ksp of AgIO3 at a given temperature is 1.0 × 10−8 , what is the mass of AgIO3 contained in 100 ml of its saturated solution? (1) 28.3 × 10−2 g (2) 2.83 × 10−3 g (3) 1.0 × 10−7 g (4) 1.0 × 10−4 g

Q58.Regular use of which of the following fertilizer increases the acidity of soil? (1) Potassium nitrate (2) Urea (3) Superphosphate of lime (4) Ammonium sulphate

Q59.The first and second dissociation constants of an acid H2A are 1.0 × 10−5 and 5.0 × 10−10 respectively. The overall dissociation constant of the acid will be JEE Main 2007 JEE Main Previous Year Paper (1) 5.0 × 10−5 (2) 5.0 × 1015 (3) 5.0 × 10−15 (4) 0.0 × 105