Question Paper JEE Mains
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
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. In a series L-C-R circuit, R = 200W and the voltage and the frequency of the main supply is 220 V and 50 Hz respectively. On taking out the capacitance from the circuit the current lags behind the voltage by 30°. On taking out the inductor from the circuit, the current leads the voltage by 30°. The power dissipated in the L-C-R circuit is
5. As the beam enters the medium, it will
6. The initial shape of the wavefront of the beam is
4. In a series L-C-R circuit, R = 200W and the voltage and the frequency of the main supply is 220 V and 50 Hz respectively. On taking out the capacitance from the circuit the current lags behind the voltage by 30°. On taking out the inductor from the circuit, the current leads the voltage by 30°. The power dissipated in the L-C-R circuit is
(a) 305 W
(b) 210W
(b) 210W
(c) zero
(d) 242 W
(d) 242 W
Ans. d
5. As the beam enters the medium, it will
(a) diverge
(b) converge
(c) diverge near the axis and converge near the periphery
(d) travel as a cylindrical beam
Ans. b
6. 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
Ans. d
7. 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
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 edge length of a face centered cubic cell of an ionic substance is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is
10. The edge length of a face centered cubic cell of an ionic substance is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is
(a) 288 pm
(b) 398 pm
(b) 398 pm
(c) 618 pm
(d) 144 pm
Ans. d
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(d) 144 pm
Ans. d
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