Practice Questions

Q28.For the following circuit and given inputs A and B, choose the correct option for output ‵Y ′ JEE Main 2023 (13 Apr Shift 1) JEE Main Previous Year Paper (1) (2) (3) (4)

Q28.The ratio of the density of oxygen nucleus (168O) and helium nucleus (42He) is (1) 4 : 1 (2) 8 : 1 (3) 1 : 1 (4) 2 : 1

Q28.Which of the following statement is not correct in the case of light emitting diodes? A. It is a heavily doped p-n junction. B. It emits light only when it is forward biased. C. It emits light only when it is reverse biased. D. The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used. Choose the correct answer from the options given below : (1) C and D (2) A (3) C (4) B

Q28.The energy of He+ ion in its first state is, (The ground state energy for the Hydrogen atom −13. 6 eV): (1) −27. 2 eV (2) −3. 4 eV (3) −13. 6 eV (4) −54. 4 eV

Q28.The work functions of Aluminium and Gold are 4. 1 eV and 5. 1 eV respectively. The ratio of the slope of the stopping potential versus frequency plot for Gold to that of Aluminium is (1) 1. 24 (2) 2 (3) 1 (4) 1. 5

Q29.If the height of transmitting and receiving antennas are 80 m each, the maximum line of sight distance will be : Given : Earth’s radius = 6. 4 × 106 m . (1) 32 km (2) 28 km (3) 36 km (4) 64 km

Q29.Choose the correct statement about Zener diode: (1) It works as a voltage regulator in reverse bias and (2) It works as a voltage regulator in both forward behaves like simple p-n junction diode in forward and reverse bias bias (3) It works a voltage regulator only in forward bias (4) It works as a voltage regulator in forward bias and behaves like simple p-n junction diode in reverse bias

Q29.In an n-p-n common emitter (CE) transistor the collector current changes from 5 mA to 16 mA for the change in base current from 100 μA and 200 μA, respectively. The current gain of transistor is _____. (1) 110 (2) 210 (3) 0. 9 (4) 9

Q29.The modulation index for an A.M. wave having maximum and minimum peak to peak voltages of 14 mV and 6 mV respectively is : (1) 1. 4 (2) 0. 4 (3) 0. 2 (4) 0. 6

Q30.The radius of fifth orbit of Li+ + is_______ × 10-12 m . Take: radius of hydrogen atom = 0 . 51 A

Q30.Match List I with List II LIST I LIST II A AM Broadcast I 88 −108 MHz B FM Broadcast II 540 −1600 kHz C Television III 3. 7 −4. 2 GHz D Satellite Communication IV 54 MHz − 590 MHz Choose the correct answer from the options given below: (1) A-II, B-I, C-IV, D-III (2) A-IV, B-III, C-I, D-II (3) A-II, B-III, C-I, D-IV (4) A-I, B-III, C-II, D-IV

Q30.A message signal of frequency 5 kHz is used to modulate a carrier signal of frequency 2 MHz . The bandwidth for amplitude modulation is: (1) 5 kHz (2) 20 kHz (3) 10 kHz (4) 2. 5 kHz

Q30.For an amplitude modulated wave the minimum amplitude is 3 V , while the modulation index is 60%. The maximum amplitude of the modulated wave is: (1) 5 V (2) 15 V (3) 12 V (4) 10 V

Q30.Match List-I with List-II List-I List-II (Layer of atmosphere) (Approximate height over earth's surface) (A) F1−Layer (I) 10 km (B) D−Layer (II) 170 −190 km (C) Troposphere (III) 100 km (D) E−Layer (V) 65 −75 km Choose the correct answer from the options given below. (1) A– II, B– IV, C–I, D– III (2) A– II, B– IV, C– III, D–I (3) A– III, B– IV, C–I, D– II (4) A– II, B–I, C– IV, D– III

Q30.In satellite communication, the uplink frequency band used is: (1) 420 −890 MHz (2) 5. 925 −6. 425 GHz (3) 76 −88 MHz (4) 3. 7 −4. 2 GHz

Q30.An atom absorbs a photon of wavelength 500 nm and emits another photon of wavelength 600 nm. The net energy absorbed by the atom in this process is 𝑛× 10-4eV. The value of 𝑛 is [Assume the atom to be JEE Main 2023 (13 Apr Shift 2) JEE Main Previous Year Paper stationary during the absorption and emission process] (Take ℎ= 6 . 6 × 10-34J s and 𝑐= 3 × 108 m s-1 ). Q31.. Identify the correct order of standard enthalpy of formation of sodium halides. (1) NaI < NaBr < NaF < NaCl (2) NaI < NaBr < NaCl < NaF (3) NaF < NaCl < NaBr < NaI (4) NaCl < NaF < NaBr < NaI

Q30.In an amplitude modulation, a modulating signal having amplitude of X V is superimposed with a carrier signal of amplitude Y V in first case. Then, in second case, the same modulating signal is superimposed with different carrier signal of amplitude 2Y V. The ratio of modulation index in the two case respectively wil be : (1) 1 : 2 (2) 1 : 1 (3) 2 : 1 (4) 4 : 1

Q30.Match List I with List II List I List II AAttenuation I Combination of a receiver and transmitter Process of retrieval of information from the carrier wave at B Transducer II receiver C DemodulationIII Converts one form of energy into another of strength of a signal while propagating through a DRepeater IVLoss medium JEE Main 2023 (30 Jan Shift 2) JEE Main Previous Year Paper Choose the correct answer from the options given below : (1) A-I, B-II, C-III, D-IV (2) A-II, B-III, C-IV, D-I (3) A-IV, B-III, C-I, D-II (4) A-IV, B-III, C-II, D-I

Q31.The number of molecules and moles in 2 . 8375 litres of O2 at STP are respectively (1) 7 . 527 × 1023 and 0 . 125 mol (2) 7 . 527 × 1022 and 0 . 250 mol (3) 1 . 505 × 1023 and 0 . 250 mol (4) 7 . 527 × 1022 and 0 . 125 mol

Q31.It is observed that characteristic X-ray spectra of elements show regularity. When frequency to the power 'n' i.e. vn of X-rays emitted is plotted against atomic number Z, the following graph is obtained. The value of 'n' is JEE Main 2023 (24 Jan Shift 1) JEE Main Previous Year Paper (1) 1 (2) 2 1 (3) (4) 3 2

Q31.Assume that the radius of the first Bohr orbit of hydrogen atom is 0. 6Å . The radius of the third Bohr orbit of He+ is _____ picometer. (Nearest Integer)

Q31.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: Hydrogen is an environment friendly fuel. Reason R: Atomic number of hydrogen is 1 and it is a very light element. In the light of the above statements, choose the correct answer from the options given below (1) A is true but R is false (2) Both A and R are true but R is NOT the correct explanation of A (3) A is false but R is true (4) Both A and R are true and R is the correct explanation of A

Q31.A solution is prepared by adding 2 g of ′′X′′ to 1 mole of water. Mass percent of ′′X′′in solution is (1) 5% (2) 20% (3) 2% (4) 10% JEE Main 2023 (11 Apr Shift 2) JEE Main Previous Year Paper

Q31.Match List - I with List - II LIST-II LIST-I (Block of periodic (Atomic number) table) (A) 37 I. p-block (B) 78 II. d-block JEE Main 2023 (30 Jan Shift 1) JEE Main Previous Year Paper (C) 52 III. f-block (D) 65 IV. s-block Choose the correct answer from the options given below: (1) A - II, B - IV, C - I, D - III (2) A - I, B - III, C - IV, D - II (3) A - IV, B - III, C - II, D - I (4) A - IV, B - II, C - I, D - III

Q31.Which of the following have same number of significant figures? (A) 0. 00253 (B) 1. 0003 (C) 15. 0 (D) 163 Choose the correct answer from the options given below (1) A, B and C only (2) C and D only (3) B and C only (4) A, C and D only