Practice Questions

Q29.The radius of curvature of each surface of a convex lens having refractive index 1 . 8 is 20 cm. The lens is now immersed in a liquid of refractive index 1 . 5. The ratio of power of lens in air to its power in the liquid will be 𝑥: 1. The value of 𝑥 is

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

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

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.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.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.The decay constant for a radioactive nuclide is 1 . 5 × 10-5 s-1. Atomic weight of the substance is 60 g mole-1, 𝑁𝐴= 6 × 1023. The activity of 1 . 0 µ g of the substance is ________ × 1010 Bq.

Q30.As per given figure A, B and C are the first, second and third excited energy levels of hydrogen atom n will be e. λ2 respectively. If the ratio of the two wavelengths (i. λ1 ) is 4n7 , then the value of

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.In a metre bridge experiment the balance point is obtained if the gaps are closed by 2 Ω and 3 Ω. A shunt of X Ω is added to 3 Ω resistor to shift the balancing point by 22. 5 cm. The value of X is ______.

Q2. The velocity of the bullet becomes one third after it penetrates 4 cm in a wooden block. Assuming that bullet is facing a constant resistance during its motion in the block. The bullet stops completely after travelling at (4 + x) cm inside the block. The value of x is (1) 2. 0 (2) 1. 0 (3) 0. 5 (4) 1. 5

Q7. The efficiency of a Carnot's engine, working between steam point and ice point, will be (1) 26. 81% (2) 37. 81% (3) 47. 81% (4) 57. 81%

Q7. A steel wire of length 3. 2 m(YS = 2. 0 × 1011 N m−2) and a copper wire of length 4. 4 m (YC = 1. 1 × 1011 N m−2) , both of radius 1. 4 mm are connected end to end. When stretched by a load, the net elongation is found to be 1. 4 mm. The load applied, in Newton, will be: (Given π = 227 ) (1) 360 (2) 180 (3) 1080 (4) 154

Q11.An aluminium wire is stretched to make its length, 0. 4% larger. The percentage change in resistance is (1) 0. 4% (2) 0. 2% (3) 0. 8% (4) 0. 6%

Q12.A compass needle of oscillation magnetometer oscillates 20 times per minute at a place P of dip 30° . The number of oscillations per minute become 10 at another place Q of 60° dip. The ratio of the total magnetic field at the two places (BQ : BP) is: (1) √3 : 4 (2) 4 : √3 (3) √3 : 2 (4) 2 : √3 JEE Main 2022 (27 Jul Shift 2) JEE Main Previous Year Paper

Q13.A cyclotron is used to accelerate protons. If the operating magnetic field is 1. 0 T and the radius of the cyclotron 'dees' is 60 cm, the kinetic energy of the accelerated protons in MeV will be : [use mp = 1. 6 × 10−27 kg, e = 1. 6 × 10−19 C] (1) 12 (2) 18 (3) 16 (4) 32

Q14.A series LCR circuit has L = 0. 01 H, R = 10 Ω and C = 1 μF and it is connected to ac voltage of amplitude (Vm) 50 V . At frequency 60% lower than resonant frequency, the amplitude of current will be approximately (1) 466 mA (2) 312 mA (3) 238 mA (4) 196 mA

Q14.The magnetic flux through a coil perpendicular to its plane is varying according to the relation ϕ = (5t3 + 4t2 + 2t −5) Weber. If the resistance of the coil is 5 ohm , then the induced current through the coil at t = 2 s will be, (1) 15. 6 A (2) 16. 6 A (3) 17. 6 A (4) 18. 6 A

Q16.Two coherent sources of light interfere. The intensity ratio of two sources is 1 : 4. For this interference pattern if the value of Imax+Imin is equal to 2α+1 , then α will be Imax−Imin β+3 β (1) 1. 5 (2) 2 (3) 0. 5 (4) 1

Q18.The activity of a radioactive material is 6. 4 × 10−4 curie. Its half life is 5 days. The activity will become 5 × 10−6 curie after (1) 7 days (2) 15 days (3) 25 days (4) 35 days JEE Main 2022 (27 Jul Shift 2) JEE Main Previous Year Paper

Q18.How many alpha and beta particles are emitted when Uranium 92U238 decays to lead 82 Pb206 ? (1) 3 alpha particles and 5 beta particles (2) 6 alpha particles and 4 beta particles (3) 4 alpha particles and 5 beta particles (4) 8 alpha particles and 6 beta particles

Q19.For a constant collector-emitter voltage of 8 V , the collector current of a transistor reached to the value of 6 mA from 4 mA , whereas base current changed from 20 μA to 25 μA value. If transistor is in active state, small signal current gain (current amplification factor) will be (1) 240 (2) 400 (3) 0. 0025 (4) 200