Practice Questions

Q30.Diameter of a steel ball is measured using a Vernier calipers which has divisions of 0.1 cm on its main scale (MS) and 10 divisions of its Vernier scale (VS) match 9 divisions on the main scale. Three such measurements for a ball are given as: S.No. MS (cm) VS divisions 1. 0.5 8 2. 0.5 4 3. 0.5 6 If the zero error is - 0.03 cm, then mean corrected diameter is: (1) 0. 53 cm (2) 0. 56 cm (3) 0. 59 cm (4) 0. 52 cm

Q30.A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. The frequencies of the resultant signal is/are: JEE Main 2015 (04 Apr) JEE Main Previous Year Paper (1) 2000 kHz and 1995 kHz (2) 2 MHz only (3) 2005 kHz and 1995 kHz (4) 2005 kHz, 2000 kHz and 1995 kHz

Q30.The value of the resistor, RS , needed in the DC voltage regulator circuit shown here, equals: (1) (Vi+VL) (2) (Vi−VL) (n+1)IL n IL (3) (Vi+VL) (4) (Vi−VL) n IL (n+1)IL JEE Main 2015 (11 Apr Online) JEE Main Previous Year Paper

Q31.A 2 V battery is connected across AB as shown in the figure. The value of the current supplied by the battery when in first case battery's positive terminal is connected to A and in second case when positive terminal of battery is connected to B will respectively be: (1) 0.2 A and 0.1 A (2) 0.1 A and 0.2 A (3) 0.2 A and 0.4 A (4) 0.4 A and 0.2 A

Q31.A sample of a hydrate of barium chloride weighing 61 g was heated until all the water of hydration is removed. The dried sample weighed 52 g. The formula of the hydrated salt is: (atomic mass, Ba = 137 amu, Cl = 35.5 amu) (1) BaCl2 ⋅H2O (2) BaCl2 ⋅3H2O (3) BaCl2 ⋅4H2O (4) BaCl2 ⋅2H2O JEE Main 2015 (10 Apr Online) JEE Main Previous Year Paper

Q31.The molecular formula of a commercial resin used for exchanging ions in water softening is C8H7SO3Na (molecular weight = 206). What would be the maximum uptake of Ca2+ ions by the resin if expressed in mol per gm? (1) 1 (2) 1 412 103 (3) 1 (4) 2 206 309

Q32.If the principal quantum number n = 6, the correct sequence of filling of electrons will be: (1) ns →(n −1) d →(n −2) f →np (2) ns →np →(n −1)d →(n −2)f (3) ns →(n −2)f →np →(n −1)d (4) ns →(n −2)f →(n −1)d →np

Q32.In the following reaction: A + 2B + 3C ⇌AB2C3 6. 0 g of A, 6.0 × 1023 atoms of B and 0. 036 mol of C reacted and formed 4. 8 g of compound AB2C3 . If the atomic mass of A and C are 60 and 80 amu, respectively. What is the atomic mass of B in amu ? (Avogadro number = 6 × 1023 ) (1) 40 amu (2) 60 amu (3) 70 amu (4) 50 amu

Q32.Which of the following is the energy of a possible excited state of hydrogen? (1) +6.8 eV (2) +13.6 eV (3) −6.8 eV (4) −3.4 eV

Q33.The ionic radii (in Å) of N3−, O2− and F− are respectively: (1) 1. 71, 1. 36 and 1. 40 (2) 1. 36, 1. 40 and 1. 71 (3) 1. 36, 1. 71 and 1. 40 (4) 1. 71, 1. 40 and 1. 36

Q33.In the long form of the periodic table, the valence shell electronic configuration of 5s25p4 corresponds to the element present in: (1) Group 16 and period 5 (2) Group 17 and period 5 (3) Group 16 and period 6 (4) Group 17 and period 6

Q33.An element X shows +3, oxidation state in its compounds. Out of the four compounds given below, choose the incorrect formula for the element X . (1) X2O3 (2) X2(SO4)3 (3) XPO4 (4) X2Cl3

Q34.The shape of XeOF4 by VSEPR theory is: (1) Trigonal bipyramidal (2) Square pyramidal (3) Pentagonal planar (4) Octahedral

Q34.At temperature T , the average kinetic energy of any particle is 32 kT. The de Broglie wavelength follows the order: (1) Visible photon >thermal electron >thermal (2) Thermal neutron >visible photon >thermal neutron. electron. (3) Thermal neutron >thermal electron >visible (4) Visible photon >thermal neutron >thermal photon. electron.

Q34.The intermolecular interaction that is dependent on the inverse cube of distance between the molecules is: (1) Hydrogen bond (2) Ion-ion interaction (3) Ion-dipole interaction (4) London force

Q35.The following reaction is performed at 298 K. 2NO(g) + O2(g) ⇌2NO2(g) The standard free energy of the formation of NO(g) is 86. 6 kJ mol−1 at 298 K. What is the standard free energy of the formation of NO2(g) at 298 K? (KP = 1.6 × 1012) (1) 0.5[2 × 86,600 −R(298) ln (1.6 × 1012)] (2) R(298) ln(1.6 × 1012)−86,600 (3) 86,600 + R(298) ln (1.6 × 1012) (4) 86,600 − ln(1.6×1012)R(298)

Q35.Molecule AB has a bond length of 1.617 Å and a dipole moment of 0.38 D. The fractional charge on each atom(absolute magnitude) is: (e0 = 4.802 × 10−10 esu) (1) 0.5 (2) 0.05 (3) 0 (4) 1.0

Q35.After understanding the assertion and reason, choose the correct option. Assertion: In the bonding molecular orbital (MO) of H2, electron density is increased between the nuclei. Reason: The bonding MO is ψA + ψB , which shows destructive interference of the combining electron waves. (1) Assertion and Reason are correct, but Reason is (2) Assertion and Reason are correct and Reason is not the correct explanation for the Assertion. the correct explanation for the Assertion. (3) Assertion is incorrect, Reason is correct. (4) Assertion is correct, Reason is incorrect.

Q36.Which of the following is not an assumption of the kinetic theory of gases? (1) Collisions of gas particles are perfectly elastic. (2) A gas consists of many identical particles which are in continual motion. (3) At high pressure, gas particles are difficult to (4) Gas particles have negligible volume. compress.

Q36.Which compounds exhibits maximum dipole moment among the following? JEE Main 2015 (11 Apr Online) JEE Main Previous Year Paper (1) (2) (3) (4)

Q36.The standard Gibbs energy change at 300 K for the reaction 2A ⇌B + C is 2494.2 J. At a given time, the composition of the reaction mixture is [A] = 21 , [B] = 2 and [C] = 12 . The reaction proceeds in the: [R = 8.314 J/K −mol , e = 2.718 ] {Given antilog (-0.44)=0.36} (1) Reverse direction because Q < KC (2) Forward direction because Q > KC (3) Reverse direction because Q > KC (4) Forward direction because Q < KC

Q37.The heat of atomization of methane and ethane are 360 kJ mol−1 and 620 kJ mol−1 , respectively. The longest wavelength of light capable of breaking the C −C bond is (Avogadro's number = 6.023 × 1023, h = 6.62 × 10−34 J s) (1) 2.48 × 104 nm (2) 1.49 × 104 nm (3) 2.48 × 103 nm (4) 1.49 × 103 nm

Q37.From the following statements, choose the incorrect statement regarding H2O2 . (1) It has to be kept away from dust. (2) It can act only as an oxidising agent. (3) It decomposes on exposure to light. (4) It has to be stored in plastic or wax-lined glass bottles in the dark.

Q37.When does a gas deviate the most from its ideal behavior? (1) At low pressure and high temperature (2) At high pressure and high temperature (3) At low pressure and low temperature (4) At high pressure and low temperature

Q38.Which one of the following alkaline earth metal sulphates has its hydration enthalpy greater than its lattice enthalpy? (1) SrSO4 (2) CaSO4 (3) BeSO4 (4) BaSO4 JEE Main 2015 (04 Apr) JEE Main Previous Year Paper