Practice Questions

Q30.A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it ? (1) A meter scale (2) A vernier calliper where the 10 divisions in vernier scale matches with 9 division in main scale and main scale has 10 divisions in 1 cm (3) A screw gauge having 100 divisions in the (4) A screw gauge having 50 divisions in the circular circular scale and pitch as 1 mm scale and pitch as 1 mm

Q30.A Zener diode is connected to a battery and a load as show below: The currents, I, IZ and IL are respectively. (1) 15 mA, 5 mA, 10 mA (2) 15 mA, 7.5 mA, 7.5 mA (3) 12.5 mA, 5 mA, 7.5 mA (4) 12.5 mA, 7.5 mA, 5 mA

Q31.A gaseous compound of nitrogen and hydrogen contains 12.5% (by mass) of hydrogen. The density of the compound relative to hydrogen is 16. The molecular formula of the compound is: (1) NH2 (2) N3H (3) NH3 (4) N2H4 JEE Main 2014 (11 Apr Online) JEE Main Previous Year Paper

Q31.The ionization energy of gaseous Na atoms is 495. 5 kJ mol−1 . The lowest possible frequency of light that ionizes a sodium atom is (h = 6.626 × 10−34 Js, NA= 6.022 × 1023 mol−1) (1) 1.24 × 1015 s−1 (2) 7.50 × 104 s−1 (3) 4.76 × 1014 s−1 (4) 3.15 × 1015 s−1

Q31.Dissolving 120 g of a compound of (mol. wt. 60) in 1000 g of water gave a solution of density 1.12 g/mL. The molarity of the solution is : (1) 2.50 M (2) 1.00 M (3) 2.00 M (4) 4.00 M

Q31.The amount of BaSO4 formed upon mixing 100 mL of 20.8%BaCl2 solution with 50 mL of 9.8% H2SO4 solution will be: (Ba = 137, Cl = 35.5, S = 32, H = 1 and O = 16 ) (1) 23.3 g (2) 11.65 g (3) 30.6 g (4) 33.2 g

Q32.Which one of the following has largest ionic radius ? (1) F− (2) B3+ (3) O2− (4) Li+

Q32.If λ0 and λ be threshold wavelength and wavelength of incident light, the velocity of photoelectron ejected from the metal surface is: m (λo (1) √2hm (λ0 −λ) (2) √2hc −λ) m ( λo −1λ ) (3) √2hc λ0−λ (4) 1 m ( λλ0 ) √2h

Q32.The correct set of four quantum numbers for the valence electrons of rubidium atom (Z = 37) is (1) 5, 0, 0, + 21 (2) 5, 1, 0, + 12 (3) 5, 1, 1, + 12 (4) 5, 0, 1, + 12

Q33.Based on the equation: 1 ΔE = −2.0 × 10−18 J ( n22 −1n21 ) the wavelength of the light that must be absorbed to excite hydrogen electron from level n = 1 to level n = 2 will be: (h = 6.625 × 10−34Js, C = 3 × 108 ms−1) (1) 1.325 × 10−7 m (2) 1.325 × 10−10 m (3) 2.650 × 10−7 m (4) 5.300 × 10−10 m

Q33.Which one of the following molecules is paramagnetic? (1) N2 (2) O3 (3) CO (4) NO

Q33.Which one of the following properties is not shown by NO ? (1) It is diamagnetic in gaseous state (2) It is a neutral oxide (3) It combines with oxygen to form nitrogen (4) It's bond order is 2.5 dioxide

Q33.The energy of an electron in first Bohr's orbit of H atom is −13.6 eV. The energy value of electron in the first excited state of Li2+ is : (1) 27.2 eV (2) −30.6 eV (3) 30.6 eV (4) −27.2 eV

Q34.Sulphur dioxide and oxygen were allowed​ to diffuse through a porous partition. 20 dm3 of SO2 diffuses through the porous partition in 60 seconds. The volume of O2 in dm3 which diffuses under the similar condition in 30 seconds will be (atomic mass of sulphur = 32 u ); JEE Main 2014 (19 Apr Online) JEE Main Previous Year Paper (1) 28. 2 (2) 10. 0 (3) 14. 1 (4) 7. 09

Q34.In the following sets of reactants which two sets best exhibit the amphoteric character of Al2O3 . xH2O ? Set I Al2O3 ⋅xH2O(s) + OH−(aq) Set II Al2O3x ⋅H2O(s) + H2O(l) Set III Al2O3x ⋅H2O(s) + H+(aq) Set IV Al2O3 ⋅xH2O(s) + NH3(aq) (1) 2 and 4 (2) 1 and 2 (3) 1 and 3 (4) 3 and 4

Q34.Which of the following series correctly represents relations between the elements from X to Y ? X →Y (1) 3Li →19 K Ionization enthalpy increases (2) 9 F →35Br Electron gain enthalpy (negative sign) increases (3) 6C →32Ge Atomic radii increases (4) 18Ar →54Xe Noble character increases

Q34.For which of the following molecule significant μ ≠0 ? (1) Only (a) (2) (a) and (b) (3) Only (c) (4) (c) and (d)

Q35.For the decomposition of the compound, represented as NH2COONH4(s) ⇌2NH3(g) + CO2(g) the Kp = 2 .9 ×10−5 atm3 . If the reaction is started with 1 mole of the compound, the total pressure at equilibrium would be : (1) 7 .66 ×10−2 atm (2) 38 .8 ×10−2 atm (3) 5 .82 ×10−2 atm (4) 1 .94 ×10−2 atm

Q35.If Z is the compressibility factor, then Van der Waal's equation at low pressure can be written as: JEE Main 2014 (06 Apr) JEE Main Previous Year Paper (1) Z = 1 + RTPb (2) Z = 1 − VRTa (3) Z = 1 −PbRT (4) Z = 1 + RTPb

Q35.The correct order of bond dissociation energy among N2, O2, O−2 is shown in which of the following arrangements? (1) N2 > O−2 > O2 (2) O−2 > O2 > N2 (3) N2 > O2 > O−2 (4) O2 > O−2 > N2

Q35.The number and type of bonds in C2−2 ion in CaC2 are: (1) Two σ -bonds and two π-bonds (2) One σ -bond and two π-bonds (3) One σ -bond and one π-bond (4) Two σ -bonds and one π-bond

Q36.Zirconium phosphate [Zr3 (PO4)4] dissociates into three zirconium cations of charge​ +4 and four phosphate anions of charge −3. If molar solubility of zirconium phosphate is denoted by s and its solubility product by Ksp then which of the following relationship between s and Ksp is correct ​? (1) S = {Ksp/6912}7 (2) S = {Ksp/144}1/7 (3) S = {Ksp/(6912)1/7} (4) S = (Ksp/6912)1/7

Q36.Which of the following arrangements represents the increasing order (smallest to largest) of ionic radii of the given species O2−, S2−, N3−, P3− ? JEE Main 2014 (12 Apr Online) JEE Main Previous Year Paper (1) O2−< N3−< S2−< P3− (2) O2−< P3−< N3−< S2− (3) N3 < O2−< P3−< S2− (4) N3−< S2−< O2−< P3−

Q36.Which of the following has unpaired electron(s)? (1) O−2 (2) N2+2 (3) O2−2 (4) N2

Q36.For complete combustion of ethanol, C2H5OH(l) + 3O2(g) →2CO2(g) + 3H2O(l), the amount of heat produced as measured in bomb calorimeter, is 1364.47 kJ mol−1 at 25℃ . Assuming ideality the Enthalpy of combustion, ΔcH , for the reaction will be: (R = 8.314 kJ mol−1) (1) −1366.95 kJ mol−1 (2) −1361.95 kJ mol−1 (3) −1460.50 kJ mol−1 (4) −1350.50 kJ mol−1