Practice Questions

Q45.If there are n capacitors in parallel connected to V volt source, then the energy stored is equal to (1) CV (2) 12 nCV2 (3) CV2 (4) 2n1 CV 2

Q48.A wire when connected to 220 V mains supply has power dissipation P1 . Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is P2 Then P2 : P1 is (1) 1 (2) 4 (3) 2 (4) 3

Q51. If in the circuit, power dissipation is 150 W, then R is (1) 2Ω (2) 6Ω (3) 5Ω (4) 4Ω JEE Main 2002 JEE Main Previous Year Paper

Q53.If an electron and a proton having same momenta enter perpendicular to a magnetic field, then (1) curved path of electron and proton will be same (2) they will move undeflected (ignoring the sense of revolution) (3) curved path of electron is more curved than that (4) path of proton is more curved of the proton

Q54.Wires 1 and 2 carrying currents i1 and i2 respectively are inclined at an angle θ to each other. What is the force on a small element dl of wire 2 at a distance of r from wire 1 (as shown in the figure) due to the magnetic field of wire 1 ? μ0 (1) θ 2πr i1i2dl tan θ (2) 2πrμ0 i1i2 dl sin (3) 2πr μ0 i1i2dl cos θ (4) 4πrμ0 i1i2dl sin θ

Q56.A conducting square loop of side L and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A magnetic induction B constant in time and space, pointing perpendicular and into the plane at the loop exists everywhere with half the loop outside the field, as shown in figure. The induced emf is (1) zero (2) RvB (3) VBL/R (4) VBL

Q57. The inductance between A and D is (1) 3.66 H (2) 9 H (3) 0.66 H (4) 1 H JEE Main 2002 JEE Main Previous Year Paper

Q64.An astronomical telescope has a large aperture to (1) reduce spherical aberration (2) have high resolution (3) increase span of observation (4) have low dispersion

Q67.Wavelength of light used in an optical instrument are λ1 = 4000Å and λ2 = 5000Å, then ratio of their respective resolving powers (corresponding to λ1 and λ2 ) is (1) 16 : 25 (2) 9 : 1 (3) 4 : 5 (4) 5 : 4

Q68.Sodium and copper have work functions 2.3eV and 4.5eV respectively. Then the ratio of the wave lengths is nearest to JEE Main 2002 JEE Main Previous Year Paper (1) 1 : 2 (2) 4 : 1 (3) 2 : 1 (4) 1 : 4

Q69.Formation of covalent bonds in compounds exhibits (1) wave nature of electron (2) particle nature of electron (3) both wave and particle nature of electron (4) none of these

Q71.At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound can emit (i) electrons (ii) protons (iii) He2+ (iv) neutrons The emission at instant can be (1) i, ii, iii (2) i, ii, iii, iv (3) iv (4) ii, iii

Q73.If mass-energy equivalence is taken into account, when water is cooled to form ice, the mass of water should (1) increase (2) remain unchanged (3) decrease (4) first increase then decrease

Q77.In a compound C, H and N atoms are present in 9 : 1 : 35 by weight. Molecular weight of compound is 108. Molecular formula of compound is (1) C2H6N2 (2) C3H4N (3) C6H8N2 (4) C9H12N3

Q80.Uncertainity in position of a minute particle of mass 25 g in space is 10−5 m. What is the uncertainity in its velocity (in ms−1)? ( h = 6.6 × 10−34Js) (1) 2.1 × 10−34 (2) 0.5 × 10−34 (3) 2.1 × 10−28 (4) 0.5 × 10−23 Q81. β - particle is emitted in radioactivity by (1) conversion of proton to neutron (2) from outermost orbit (3) conversion of neutron to proton (4) β-particle is not emitted

Q84.Which of the following statements is true ? (1) HF is less polar than HBr (2) absolutely pure water does not contain any ions (3) chemical bond formation take place when forces (4) in covalency transference of electron takes place of attraction overcome the forces of repulsion

Q85.For an ideal gas, number of moles per litre in terms of its pressure P, gas contant R and temperature T is (1) PT/R (2) PRT (3) P/RT (4) RT/P

Q89.A heat engine absorbs heat Q1 at temperature T1 and heat Q2 at temperature T2 . Work done by the engine is J (Q1 + Q2). This data (1) violates 1st law of thermodynamics (2) violates 1st law of thermodynamics if Q1 is −ve (3) violates 1st law of thermodynamics if Q2 is − ve(4) does not violate 1st law of thermodynamics

Q90.The heat required to raise the temperature of body by 1 K is called JEE Main 2002 JEE Main Previous Year Paper (1) specific heat (2) thermal capacity (3) water equivalent (4) none of these

Q92.In which of the following reactions, increase in the volume at constant temperature does not affect the number of moles at equilibrium (1) 2NH3 →N2 + 3H2 (2) C(g) + (1/2)O2( g) →CO(g) (3) H2( g) + O2( g) →H2O2( g) (4) none of these

Q96.Let the solubility of an aqueous solution of Mg(OH)2 be x then its ksp is (1) 4x3 (2) 108x5 (3) 27x4 (4) 9x