Practice Questions

Q48.When 3Li′ nuclei are bombarded by protons, and the resultant nuclei are 4Be8 , the emitted particles will be JEE Main 2006 JEE Main Previous Year Paper (1) neutrons (2) alpha particles (3) beta particles (4) gamma photons

Q49.A solid which is transparent to visible light and whose conductivity increases with temperature is formed by (1) Metallic binding (2) Ionic binding (3) Covalent binding (4) Van der Waals binding

Q51.If the binding energy per nucleon in 73Li and 42He nuclei are 5.60MeV and 7.06MeV respectively, then in the reaction p + 73Li →242He energy of proton must be (1) 39.2MeV (2) 28.24MeV (3) 17.28MeV (4) 1.46MeV

Q52.If the ratio of the concentration of electrons that of holes in a semiconductor is 7 and the ratio of currents is 7 , 5 4 then what is the ratio of their drift velocities? (1) 4 (2) 5 7 8 (3) 4 (4) 5 5 4

Q56.The circuit has two oppositely connect ideal diodes in parallel. What is the current following in the circuit? (1) 1.33 A (2) 1.71 A (3) 2.00 A (4) 2.31 A

Q58.Density of a 2.05M solution of acetic acid in water is 1.02 g/mL . The molality of the solution is (1) 1.14 mol kg−1 (2) 2.28 mol kg−1 (3) 3.28 mol kg−1 (4) 0.44 mol kg−1

Q60.In the transformation of 238 92 U to 23492 U , if one emission is an α-particle, what should be the other emission(s)? (1) Two β− (2) Two β− and one β+ (3) One β− and one γ (4) One β+ and one β−

Q61.Uncertainty in the position of an electron (mass = 9.1 × 10−31 kg ) moving with a velocity 300 ms−1 , accurate upto 0.001%, will be JEE Main 2006 JEE Main Previous Year Paper (1) 19.2 × 10−2 m (2) 5.76 × 10−2 m (3) 1.92 × 10−2 m (4) 3.84 × 10−2 m (h = 6.63 × 10−34Js)

Q63.The "spin-only" magnetic moment [in units of Bohr magneton, (μB)] of Ni2+ in aqueous solution would be (Atomic number of Ni = 28 ) (1) 2.84 (2) 4.90 (3) 0 (4) 1.73

Q64.The increasing order of the first ionization enthalpies of the elements B, P, S and F (lowest first) is (1) F < S < P < B (2) P < S < B < F (3) B < P < S < F (4) B < S < P < F

Q65.The decreasing values of bond angles from NH3 (106∘) to SbH3 (101∘) down group-15 of the periodic table is due to (1) increasing bp-bp repulsion (2) increasing p-orbital character in sp3 (3) decreasing Ip-bp repulsion (4) decreasing electronegativity

Q66.Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture? (1) The reactivity decreases in the alkali metals but (2) In both the alkali metals and the halogens the increases in the halogens with increase in atomic chemical reactivity decreases with increase in number down the group atomic number down the group (3) Chemical reactivity increases with increase in (4) In alkali metals the reactivity increases but in the atomic number down the group in both the alkali halogens it decreases with increase in atomic metals and halogens number down the group

Q67.Which of the following molecules/ions does not contain unpaired electrons? (1) O2−7 (2) B2 (3) N+2 (4) O2

Q68.Among the following mixtures, dipole-dipole as the major interaction, is present in (1) benzene and ethanol (2) acetonitrile and acetone (3) KCl and water (4) benzene and carbon tetrachloride

Q69.A metal, M forms chlorides in its +2 and +4 oxidation states. Which of the following statements about these chlorides is correct? (1) MCl2 is more volatile than MCl4 (2) MCl2 is more soluble in anhydrous ethanol than MCl4 (3) MCl2 is more ionic than MCl4 (4) MCl2 is more easily hydrolysed than MCl4

Q70.In which of the following molecules/ions are all the bonds not equal? JEE Main 2006 JEE Main Previous Year Paper (1) SF4 (2) SiF4 (3) XeF4 (4) BF−4

Q71.Phosphorus pentachloride dissociates as follows, in a closed reaction vessel, PCl5( g) ⇌PCl3( g) + Cl2( g) If total pressure at equilibrium of the reaction mixture is P and degree of dissociation of PCl5 is x, the partial pressure of PCl3 will be (1) ( x+1x )P (2) ( 1−x2x )P (3) ( x−1x )P (4) ( 1−xx )P

Q72.The standard enthalpy of formation (ΔfH∘) at 298 K for methane, CH4( g), is −74.8 kJ mol−1 . The additional information required to determine the average energy for C −H bond formation would be (1) the dissociation energy of H2 and enthalpy of (2) latent heat of vapourization of methane sublimation of carbon (3) the first four ionization energies of carbon and (4) the dissociation energy of hydrogen molecule, H2 electron gain enthalpy of hydrogen

Q73.An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If Ti is the initial temperature and Tf is the final temperature, which of the following statements is correct? (1) (Tf)irev > (Tf)rev (2) Tf > Ti for reversible process but Tf = Ti for irreversible process (3) (Tf)rev = (Tf) irrev (4) Tf = Ti for both reversible and irreversible processes

Q74. Cl2( g) = 2Cl(g), 242.3 kJ mol−1 I2( g) = 2I(g), 151.0 kJ mol−1 The enthalpy changes for the following processes are listed below: ICl(g) = I(g) + Cl(g), 211.3 kJ mol−1 I2( s) = I2( g), 62.76 kJ mol−1 Given that the standard states for iodine and chlorine are I2( s) and Cl2( g), the standard enthalpy of formation for ICl(g) is (1) −14.6 kJ mol−1 (2) −16.8 kJ mol−1 (3) +16.8 kJ mol−1 (4) +244.8 kJ mol−1

Q77.Which of the following statements is true? (1) H3PO3 is a stronger acid than H2SO3 (2) In aqueous medium HF is a stronger acid than HCl (3) HClO4 is a weaker acid than HClO3 (4) HNO3 is a stronger acid than HNO2

Q78.The ionic mobility of alkali metal ions in aqueous solution is maximum for (1) K + (2) Rb+ (3) Li+ (4) Na+

Q79. (1) 2-bromo-6-chlorocyclohex-1-ene (2) 6-bromo-2-chlorocyclohexene (3) 3-bromo-1-chlorocyclohexene (4) 1-bromo-3-chlorocyclohexene

Q80.The increasing order of the rate of HCN addition to compounds A −D is (A) HCHO (B) CH3COCH3 (C) PhCOCH3 (D) PhCOPh (1) A < B < C < D (2) D < B < C < A (3) D < C < B < A (4) C < D < B < A

Q81.The increasing order of stability of the following free radicals is (1) (CH3)2 ˙CH < (CH3)3 ˙C < (C6H5)2 ˙CH < (C6H5)3(2)˙C(C6H5)3 ˙C < (C6H5)2 ˙CH < (CH3)3 ˙C < (CH3)2 ˙CH (3) (C6H5)2 ˙CH < (C6H5)3 ˙C < (CH3)3 ˙C < (CH3)2(4)˙CH(CH3)2 ˙CH < (CH3)3 ˙C < (C6H5)3 ˙C < (C6H5)2 ˙CH