MCQs JEE Main
1. A diatomic ideal gas is used in a car engine as the working substance. If during the adiabatic expansion part of the cycle, volume of the gas increases from V to 32 V, the efficiency of the engine is
(a) 0.5
(b) 0.75
(b) 0.75
(c) 0.99
(d) 0.25
(d) 0.25
Ans. b
2. If a source ol power 4 kW produces 1020 photons/second, the radiation belong to a part of the spectrum called
(a) X-rays
(b) ultraviolet rays
(b) ultraviolet rays
(c) microwaves
(d) y-rays
(d) y-rays
Ans. a
3. The respective number of significant figures for the numbers 23.023, 0.0003 & 2.1 × 10–3 are
(a) 5, 1, 2
(b) 5, 1, 5
(b) 5, 1, 5
(c) 5, 5, 2
(d) 4, 4, 2
(d) 4, 4, 2
Ans. a
4. The initial shape of the wavefront of the beam is
4. The initial shape of the wavefront of the beam is
(a) convex
(b) concave
(c) convex near the axis and concave near the periphery
(d) planar
(d) planar
Ans. d
5. The speed of light in the medium is
(a) minimum on the axis of the beam
(b) the same everywhere in the beam
(c) directly proportional to the intensity l
(d) maximum on the axis of the beam
Ans. a
6. The time for half-life period of a certain reaction, A → products is 1 h. When the initial concentration of the reactant 'A', is
2.0 mol L–1, how much time does it take for its concentration to come from 0.50 to 0.25 mol L–1, if it is a zero order reaction?
(a) 4 h
(b) 0.5 h
(b) 0.5 h
(c) 0.25 h
(d) 1 h
(d) 1 h
Ans. c
7. A solution containing 2.675 g of CoCl3.6NH3 (molar mass = 267.5 g mol–1) is passed through a cation exchanger. The chloride ions obtained in solution were treated with excess of AgNO3 to give 4.78 g of AgCl (molar mass = 143.5 g mol–1). The formula of the complex is (At mass of Ag = 108 u)
(a) [Co(NH3)6]Cl3
(b) [CoCl2(NH3)4]Cl
(b) [CoCl2(NH3)4]Cl
(c) [CoCl3(NH3)3]
(d) [CoCl(NH3)5]Cl2
(d) [CoCl(NH3)5]Cl2
Ans. a
8. One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is
8. One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is
(a) propene
(b) 1-butene
(b) 1-butene
(c) 2-butene
(d) ethene
(d) ethene
Ans. c
9. From amongst the following alcohols, the one that would react fastest with conc. HCl and anhydrous ZnCl2, is
9. From amongst the following alcohols, the one that would react fastest with conc. HCl and anhydrous ZnCl2, is
(a) 2-butanol
(b) 2-methylpropan-2-ol
(b) 2-methylpropan-2-ol
(c) 2-methylpropanol
(d) 1-butanol
(d) 1-butanol
Ans. b
10. The energy required to break one mole of Cl—Cl bonds in Cl2 is 242 kJ mol–1. The longest wavelength of light capable of breaking a single Cl—Cl bond is (c = 3t × 108 ms–1 and NA = 6.02 × 1023 mol–1)
10. The energy required to break one mole of Cl—Cl bonds in Cl2 is 242 kJ mol–1. The longest wavelength of light capable of breaking a single Cl—Cl bond is (c = 3t × 108 ms–1 and NA = 6.02 × 1023 mol–1)
(a) 594 nm
(b) 640 nm
(b) 640 nm
(c) 700 nm
(d) 494 nm
(d) 494 nm
Ans. d
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