Practice Questions

Q30. In an experiment to determine the gravitational acceleration g of a place with the help of a simple pendulum, the measured time period squared is plotted against the string length of the pendulum in the figure. What is the value of g at the place? (1) 10. 0 m s−2 (2) 9. 87 m s−2 (3) 9. 91 m s−2 (4) 9. 81 m s−2

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

Q30.For sky wave propagation, the radio waves must have a frequency range in between: (1) 1MHz to 2MHz (2) 5MHz to 25MHz (3) 35MHz to 40MHz (4) 45MHz to 50MHz

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.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 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.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

Q31.The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecules is: (1) 1 : 4 (2) 7 : 32 (3) 1 : 8 (4) 3 : 16

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

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

Q32.If m and e are the mass and charge of the revolving electron in the orbit of radius r for hydrogen atom, the total energy of the revolving electron will be: 1 e2 (1) r (2) −e2r 2 (3) me2 r (4) −12 e2r

Q32.The amount of oxygen in 3. 6 moles of water is: (1) 57. 6 g (2) 115. 2 g (3) 18. 4 g (4) 28. 8 g

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

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.The de-Broglie wavelength of a particle of mass 6.63 g moving with a velocity of 100 ms−1 is: (1) 10−33 m (2) 10−35 m (3) 10−31 m (4) 10−25 m

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.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.Excited hydrogen atom emits light in the ultraviolet region at 2.47 × 1015 Hz. With this frequency, the energy of a single photon is: (h = 6.63 × 10−34Js) (1) 8.041 × 10−40 J (2) 2.680 × 10−19 J (3) 1.640 × 10−18 J (4) 6.111 × 10−17 J

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

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

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 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