Practice Questions

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

Q30.The amplitude of 15 sin(1000 πt) is modulated by 10 sin(4 πt) signal. The amplitude modulated signal contains frequencies of A. 500 Hz B. 2 Hz C. 250 Hz D. 498 Hz E. 502 Hz Choose the correct answer from the options given below JEE Main 2023 (12 Apr Shift 1) JEE Main Previous Year Paper (1) A and B only (2) A and C only (3) A and D only (4) A, D and E only

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.A TV transmitting antenna is 98 m high and the receiving antenna is at the ground level. If the radius of the earth is 6400 km, the surface area covered by the transmitting antenna is approximately: JEE Main 2023 (08 Apr Shift 1) JEE Main Previous Year Paper (1) 1240 km2 (2) 3942 km2 (3) 4868 km2 (4) 1549 km2 Q31. 0. 5 g of an organic compound (X) with 60% carbon will produce ×10−1 g of CO2 on complete combustion.

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.If 917 Å be the lowest wavelength of Lyman series then the lowest wavelength of Balmer series will be Å.

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.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.In a screw gauge, there are 100 divisions on the circular scale and the main scale moves by 0 . 5 mm on a complete rotation of the circular scale. The zero of circular scale lies 6 divisions below the line of graduation when two studs are brought in contact with each other. When a wire is placed between the studs, 4 linear scale divisions are clearly visible while 46th division the circular scale coincide with the reference line. The diameter of the wire is ______ × 10-2 mm .

Q30.For hydrogen atom, 𝜆1 and 𝜆2 are the wavelengths corresponding to the transitions 1 and 2 respectively as 𝑥 shown in figure. The ratio of 𝜆1 and 𝜆2 is 32. The value of 𝑥 is ______.

Q30.A monochromatic light is incident on a hydrogen sample in ground state. Hydrogen atoms absorb a fraction of light and subsequently emit radiation of six different wavelengths. The frequency of incident light is 𝑥× 1015 Hz. The value of x is ________ (Given ℎ= 4 . 25 × 10-15 eVs) Q31.25 mL of silver nitrate solution ( 1M ) is added dropwise to 25 mL of potassium iodide ( 1 . 05 M ) solution. The ion(s) present in very small quantity in the solution is/are (1) I- only (2) K+only (3) NO3- only (4) Ag+ and I-both

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.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.Given below are two statements Statement I : For transmitting a signal, size of antenna (l) should be comparable to wavelength of signal (at least l = λ4 in dimension). Statement II : In amplitude modulation, amplitude of carrier wave remains constant (unchanged). In the light of the above statements, choose the most appropriate answer from the options given below JEE Main 2023 (31 Jan Shift 2) JEE Main Previous Year Paper (1) Both Statement I and Statement II are correct (2) Both Statement I and Statement II are incorrect (3) Statement I is incorrect but Statement II is (4) Statement I is correct but Statement II is correct incorrect

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.The power radiated from a linear antenna of length l is proportional to (Given, λ = Wavelength of wave): (1) λ l (2) ( λl ) 2 (3) l (4) l2 λ2 λ

Q30.Assume that protons and neutrons have equal masses. Mass of a nucleon is 1 . 6 × 10-27 kg and radius of 1 nucleus is 1 . 5 × 10-15 A 3 m. The approximate ratio of the nuclear density and water density is n × 1013. The value of n is _____.

Q30.A light of energy 12 . 75 eV is incident on a hydrogen atom in its ground state. The atom absorbs the radiation and reaches to one of its excited states. The angular momentum of the atom in the excited state is 𝑥 – 15 – 𝜋× 10-17 eVs. The value of 𝑥 is ______ (use ℎ= 4 . 14 × 10 eVs, 𝑐= 3 × 108 m s 1)

Q30.When two resistance R1 and R2 connected in series and introduced into the left gap of a meter bridge and a resistance of 10 Ω is introduced into the right gap, a null point is found at 60 cm from left side. When R1 and R2 are connected in parallel and introduced into the left gap, a resistance of 3 Ω is introduced into the right- gap to get null point at 40 cm from left end. The product of R1 R2 is ______ Ω2

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.The shortest wavelength of hydrogen atom in Lyman series is λ. The longest wavelength in Balmer series of He+ is (1) 5 (2) 9λ 9λ 5 (3) 36λ (4) 5λ 5 9

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.Given below are two statements Statement I : According to Bohr’s model of hydrogen atom, the angular momentum of an electron in a given stationary state is quantised. Statement II : The concept of electron in Bohr’s orbit, violates the Heisenberg uncertainty principle. In the light of the above statements, choose the most appropriate answer from the options given below (1) Statement I is incorrect but Statement II is (2) Both Statement I and Statement II are correct correct (3) Both Statement I and Statement II are incorrect (4) Statement I is correct but Statement II is incorrect

Q31.An organic compound gives 0. 220 g of CO2 and 0. 126 g of H2O on complete combustion. If the % of carbon is 24 then the % of hydrogen is _________ × 10–1. (Nearest integer)