Practice Questions

Q25.A capacitor of 10μF capacitance whose plates are separated by 10 mm through air and each plate has area 4 cm2 is now filled equally with two dielectric media of K1 = 2, K2 = 3 respectively as shown in figure. If new force between the plates is 8 N . The supply voltage is _________ ×10−4 V . (we modified language of question to make it correct)

Q25.A thin metallic wire having cross sectional area of 10−4 m2 is used to make a ring of radius 30 cm. A positive charge of 2π C is uniformly distributed over the ring, while another positive charge of 30 pC is kept at the centre of the ring. The tension in the ring is _______ N; provided that the ring does not get deformed (neglect the influence of gravity). (Given, 1 = 9 × 109 SI units) 4πϵ0

Q25.An electron is moving under the influence of the electric field of a uniformly charged infinite plane sheet S having surface charge density +σ. The electron at t = 0 is at a distance of 1 m from S and has a speed of 1 m s−1 . The maximum value of σ, if the electron strikes S at t = 1 s is α[ mϵ0e ] m2C . The value of α is _____.

Q26.A heater is designed to operate with a power of 1000 W in a 100 V line. It is connected in combination with a resistance of 10Ω and a resistance R, to a 100 V mains as shown in figure. For the heater to operate at 62.5 W, the value of R should be _____ Ω.

Q26.Twelve wires each having resistance 2Ω are joined to form a cube. A battery of 6 V emf is joined across point a and c. The voltage difference between e and f is ______V.

Q26.Two identical charged spheres are suspended by strings of equal lengths. The string make an angle of 37° with each other. When suspended in a liquid of density 0 . 7 g cm-3, the angle remains same. If density of material 3 of the sphere is 1 . 4 g cm-3, the dielectric constant of the liquid is _____ tan37° = 4

Q27.A square loop of edge length 2 m carrying current of 2 A is placed with its edges parallel to the x y axis. A magnetic field is passing through the x −y plane and expressed as →B = B0(1 + 4x)^k, where B0 = 5 T. The net magnetic force experienced by the loop is _______ N .

Q28.A rectangular loop of sides 12 cm and 5 cm, with its sides parallel to the 𝑥-axis and 𝑦-axis respectively moves with a velocity of 5 cm s-1 in the positive 𝑥 axis direction, in a space containing a variable magnetic field in the positive 𝑧 direction. The field has a gradient of 10-3 T cm-1 along the negative 𝑥 direction and it is decreasing with time at the rate of 10-3 T s-1 . If the resistance of the loop is 6 m𝛺, the power dissipated by the loop as heat is ______ × 10-9 W .

Q28.A square loop PQRS having 10 turns, area 3.6 × 10−3 m2 and resistance 100Ω is slowly and uniformly being pulled out of a uniform magnetic field of magnitude B = 0.5 T as shown. Work done in pulling the loop out of JEE Main 2024 (08 Apr Shift 1) JEE Main Previous Year Paper the field in 1.0 s is ______ ×10−6 J.

Q28.A small square loop of wire of side 𝑙 is placed inside a large square loop of wire of side 𝐿𝐿= 𝑙2. The loops are coplanar and their centers coincide. The value of the mutual inductance of the system is √𝑥× 10-7 H, where 𝑥= ______.

Q28.An ac source is connected in given series LCR circuit. The rms potential difference across the capacitor of 20μF is _____V.

Q29.Two slits are 1 mm apart and the screen is located 1 m away from the slits. A light of wavelength 500 nm is used. The width of each slit to obtain 10 maxima of the double slit pattern within the central maximum of the JEE Main 2024 (08 Apr Shift 2) JEE Main Previous Year Paper single slit pattern is _____ ×10−4 m

Q30.A star has 100% helium composition. It starts to convert three 4He into one 12C via triple alpha process as 4He + 4He + 4He →12C + Q. The mass of the star is 2.0 × 1032 kg and it generates energy at the rate of 5.808 × 1030 W. The rate of converting these 4He to 12C is n × 1042 s−1 , where n is _________ [ Take, mass of 4He = 4.0026u, mass of 12C = 12u ]

Q30.A hydrogen atom changes its state from n = 3 to n = 2. Due to recoil, the percentage change in the wave length of emitted light is approximately 1 × 10−n . The value of n is_____. [Given Rhc = 13.6eV, hc = 1242eVnm, h = 6.6 × 10−34 J s mass of the hydrogenatom = 1.6 × 10−27 kg ] JEE Main 2024 (04 Apr Shift 1) JEE Main Previous Year Paper

Q30.When a hydrogen atom going from n = 2 to n = 1 emits a photon, its recoil speed is x5 m s−1 . Where x = _______. (Use: mass of hydrogen atom = 1. 6 × 10−27 kg , charge of electron e = 1. 6 × 10−19 C)

Q34. List - I List - II A. Melting Point [K] I. T1 > In > Ga > A1 > B Match List I with List II B. Ionic Radius [M+3/pm] II. B > T1 > A1 ≈Ga > In Choose the C. ΔiH1 [ kJ mol−1] III. T1 > In > A1 > Ga > B D. Atomic Radius [pm] IV. B > A1 > T1 > In > Ga correct answer from the options given below: (1) A-II, B-III, C-IV, D-I (2) A-IV, B-I, C-II, D-III (3) A-I, B-II, C-III, D-IV (4) A-III, B-IV, C-I, D-II

Q37. For the given compounds, the correct order of increasing pKa value : Choose the correct answer from the options given below : (1) (B) < (D) < (C) < (A) < (E) (2) (D) < (E) < (C) < (B) < (A) (3) (E) < (D) < ( C ) < ( B ) < ( A ) (4) (E) < (D) < (B) < (A) < (C) JEE Main 2024 (09 Apr Shift 1) JEE Main Previous Year Paper

Q47.Identify the major products A and B respectively in the following set of reactions. (1) (2) (3) (4)

Q47.Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): SN2 reaction of C6H5CH2Br occurs more readily than the SN2 reaction of CH3CH2Br . Reason (R) : The partially bonded unhybridized p-orbital that develops in the trigonal bipyramidal transition state is stabilized by conjugation with the phenyl ring. In the light of the above statements, choose the most appropriate answer from the options given below : (1) (A) is correct but (R) is not correct (2) (A) is not correct but (R) is correct (3) Both (A) and (R) are correct but (R) is not the (4) Both (A) and (R) are correct and (R) is the correct explanation of (A) correct explanation of (A) JEE Main 2024 (09 Apr Shift 1) JEE Main Previous Year Paper

Q49.Which one of the following reactions is NOT possible? (1) (2) (3) (4)

Q51.Consider the following reactions NiS + HNO3 + HCl →A + NO + S + H2O A + NH4OH + H3C −C = N −OH | →B + NH4Cl + H2O The number of protons that do not involve in H3C −C = N −OH hydrogen bonding in the product B is ______.

Q51.Frequency of the de-Broglie wave of electron in Bohr's first orbit of hydrogen atom is _______ ×1013 Hz [Given : RH( Rydberg constant ) = 2.18 × 10−18 J, h (Plank's (nearest integer). constant ) = 6.6 × 10−34 J.s.]

Q52.The number of species from the following which are paramagnetic and with bond order equal to one is H2, He+2 , O+2 , N2−2 , O2−2 , F2, Ne+2 , B2

Q53.An ideal gas, Cv = 2 R, is expanded adiabatically against a constant pressure of 1 atm untill it doubles in volume. If the initial temperature and pressure is 298 K and 5 atm, respectively then the final temperature is – _______ K (nearest integer). [ Cv is the molar heat capacity at constant volume] JEE Main 2024 (06 Apr Shift 1) JEE Main Previous Year Paper ′′ −

Q55.How many compounds among the following compounds show inductive, mesomeric as well as hyperconjugation effects?