Practice Questions

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

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

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

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

Q60.Which of the following molecules is expected to rotate the plane of plane polarized light? (1) (2) (3) (4)

Q62. The IUPAC name of is (1) 1, 1−diethyl −2, 2−dimethylpentane (2) 4, 4−dimethyl −5, 5−diethylpentane (3) 5, 5−diethyl −4, 4−diemthylpentane (4) 3−ethyl −4, 4−dimethylheptane

Q66.The cell, Zn Zn2+(1M)∥Cu2+(1M) Cu (E0cell = 1.10 V) , was allowed to be completely discharged at 298 K. [Zn2+] The relative concentration of Zn2+ to Cu2+ is [ [Cu2+] ] (1) antilog (24.08) (2) 37.3 (3) 1037.3 (4) 9.65 × 104

Q68.The energies of activation for forward and reverse reactions for A2 + B2 ⇌2AB are 180 kJ mol−1 and 200 kJ mol−1 respectively. The presence of catalyst lowers the activation energy of both (forward and reverse) reactions by 100 kJ mol−1 . The enthalpy change of the reaction (A2 + B2 ⟶2AB) in the presence of catalyst will be (in kJ mol−1 ) (1) 300 (2) 120 (3) 280 (4) 20

Q69.Consider the reaction, 2A + B → Products When concentration of B alone was doubled, the half-life did not change. When the concentration of A alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is (1) L mol−1 s−1 (2) no unit (3) mol L−1 s−1 (4) s−1

Q70.A radioactive element gets spilled over the floor of a room. Its half-life period is 30 days. If the initial activity is ten times the permissible value, after how many days will it be safe to enter the room? (1) 1000 days (2) 300 days (3) 10 days (4) 100 days

Q72.Identify the incorrect statement among the following (1) d− Block elements show irregular and erratic (2) La and Lu have partially filled d orbitals and no chemical properties among themselves other partially filled orbitals (3) The chemistry of various lanthanoids is very (4) 4f and 5f orbitals are equally shielded similar

Q73.The actinoids exhibits more number of oxidation states in general than the lanthanoids. This is because JEE Main 2007 JEE Main Previous Year Paper (1) the 5f orbitals are more buried than the 4f (2) there is a similarity between 4f and 5f orbitals in orbitals their angular part of the wave function (3) the actinoids are more reactive than the (4) the 5f orbitals extend further from the nucleus lanthanoids than the 4f orbitals

Q75.Which one of the following has a square planar geometry? (1) [CoCl4]2− (2) [FeCl4]2− (3) [NiCl4]2− (4) [PtCl4]2−

Q76.Which of the following reactions will yield 2, 2−dibromopropane? (1) CH3 −C ≡CH + 2HBr ⟶ (2) CH3CH ≡CHBr + HBr ⟶ (3) CH ≡CH + 2HBr ⟶ (4) CH3 −CH = CH2 + HBr ⟶

Q78. In the following sequence of reactions, the compound ' D ' is (1) butanal (2) n−butyl alcohol (3) n−propyl alcohol (4) propanal

Q80.In the chemical reaction, CH3CH2NH2 −CHCl3 + 3KOH ⟶(A) + (B) + 3H2O, the compound (A) and (B) are respectively (1) C2H5CN and 3KCl (2) CH3CH2CONH2 and 3KCl (3) C2H5NC and K2CO3 (4) C2H5NC and 3KCl