Practice Questions

Q74.Niobium ( Nb ) and ruthenium (Ru) have " x " and " y " number of electrons in their respective 4 d orbitals. The value of x + y is ______ -.

Q74.If 1 mM solution of ethylamine produces pH = 9, then the ionization constant (Kb) of ethylamine is 10−x . The value of x is ______ (nearest integer). [The degree of ionization of ethylamine can be neglected with respect to unity.]

Q74.The possible number of stereoisomers for 5-phenylpent-4-en-2-ol is … …

Q74.Consider the following data : Heat of formation of CO2( g) = −393.5 kJ mol−1 Heat of formation of H2O(l) = −286.0 kJ mol−1 Heat of combustion of benzene = −3267.0 kJ mol−1 The heat of formation of benzene is _ kJmol−1 . (Nearest integer)

Q75.In Carius method for estimation of halogens, 180 mg of an organic compound produced 143.5 mg of AgCl . The percentage composition of chlorine in the compound is _______ \%. (Given : molar mass in gmol−1 of Ag : 108, Cl : 35.5 ) 2025 (22 Jan Shift 1) JEE Main Previous Year Paper

Q75.Given below is the plot of the molar conductivity vs √ concentration for KCl in aqueous solution. If, for the higher concentration of KCl solution, the resistance of the conductivity cell is 100Ω, then the resistance of the same cell with the dilute solution is ' x ' Ω The value of x is __________ (Nearest integer) 2025 (28 Jan Shift 1) JEE Main Previous Year Paper

Q75.The hydrocarbon (X) with molar mass 80 g mol−1 and 90% carbon has … … degree of unsaturation. 2025 (24 Jan Shift 2) JEE Main Previous Year Paper

Q75.Consider the following sequence of reactions. Total number of sp3 hybridised carbon atoms in the major product C formed is________ 2025 (23 Jan Shift 2) JEE Main Previous Year Paper

Q75.If A2B is 30% ionised in an aqueous solution, then the value of van't Hoff factor (i) is ______ ×10−1 . 2025 (29 Jan Shift 1) JEE Main Previous Year Paper

Q75.Standard entropies of X2, Y2 and XY5 are 70,50 and 110 J K−1 mol−1 respectively. The temperature in Kelvin at which the reaction 1 2 X2 + 52 Y2 ⇌XY5ΔHΘ = −35 kJ mol−1 will be at equilibrium is_______. (Nearest integer) 2025 (24 Jan Shift 1) JEE Main Previous Year Paper

Q75.Consider the following sequence of reactions to produce major product (A) Molar mass of product (A) is gmol−1 . (Given molar mass in gmol−1 of C : 12, H : 1, O : 16, Br : 80, N : 14, P : 31 ) 2025 (23 Jan Shift 1) JEE Main Previous Year Paper

Q75.The spin only magnetic moment ( μ ) value (B.M.) of the compound with strongest oxidising power among Mn2O3, TiO and VO is ____ B.M. (Nearest integer). 2025 (28 Jan Shift 2) JEE Main Previous Year Paper

Q2. Young's modulus is determined by the equation given by Y = 49000 ml cm2dyn where M is the mass and l is the extension of wire used in the experiment. Now error in Young modules (Y ) is estimated by taking data from M −l plot in graph paper. The smallest scale divisions are 5 g and 0.02 cm along load axis and extension axis respectively. If the value of M and l are 500 g and 2 cm respectively then percentage error of Y is : (1) 0.5% (2) 2% (3) 0.02% (4) 0.2%

Q3. A clock has 75 cm, 60 cm long second hand and minute hand respectively. In 30 minutes duration the tip of second hand will travel x distance more than the tip of minute hand. The value of x in meter is nearly (Take π = 3.14 ) : (1) 140.5 (2) 118.9 (3) 139.4 (4) 220.0

Q16.A proton and an electron are associated with same de-Broglie wavelength. The ratio of their kinetic energies is: (Assume h=6.63 ×10−34 J s, me = 9.0 × 10−31 kg and mp = 1836 times me ) (1) 1 : √1836 (2) 1 : 18361 (3) 1 : 1 (4) 1: 1836 √1836

Q17.Average force exerted on a non-reflecting surface at normal incidence is 2.4 × 10−4 N. If 360 W/cm2 is the light energy flux during span of 1 hour 30 minutes, Then the area of the surface is: (1) 0.2 m2 (2) 20 m2 (3) 0.1 m2 (4) 0.02 m2

Q20.The measured value of the length of a simple pendulum is 20 cm with 2 mm accuracy. The time for 50 oscillations was measured to be 40 seconds with 1 second resolution. From these measurements, the accuracy in the measurement of acceleration due to gravity is 𝑁%. The value of 𝑁 is: (1) 4 (2) 8 (3) 6 (4) 5

Q20.The diameter of a sphere is measured using a vernier caliper whose 9 divisions of main scale are equal to 10 divisions of vernier scale. The shortest division on the main scale is equal to 1 mm . The main scale reading is 2 cm and second division of vernier scale coincides with a division on main scale. If mass of the sphere is 8.635 g, the density of the sphere is: (1) 2.0 g/cm3 (2) 1.7 g/cm3 (3) 2.2 g/cm3 (4) 2.5 g/cm3 JEE Main 2024 (08 Apr Shift 1) JEE Main Previous Year Paper −−−

Q21.Two identical spheres each of mass 2 kg and radius 50 cm are fixed at the ends of a light rod so that the separation between the centers is 150 cm. Then, moment of inertia of the system about an axis perpendicular to the rod and passing through its middle point is 𝑥 kg m2, where the value of 𝑥 is 20

Q21.If →a and →b makes an angle cos−1 ( 9 ) with each other, then |→a + →b| = √2|→a −→b| value of n is ____

Q21.The resultant of two vectors →A and →B is perpendicular to →A and its magnitude is half that of →B. The angle between vectors →A and →B is ______ ∘.

Q21.A body falling under gravity covers two points A and B separated by 80 m in 2 s. The distance of upper point A from the starting point is _____m. Use g = 10 m s-2

Q21.The displacement and the increase in the velocity of a moving particle in the time interval of t to (t + 1) s are 125 m and 50 m s−1 , respectively. The distance travelled by the particle in (t + 2)th s is ___________ m .

Q21.A ball rolls off the top of a stairway with horizontal velocity u. The steps are 0. 1 m high and 0. 1 m wide. The minimum velocity u with which that ball just hits the step 5 of the stairway will be √x m s−1 , where x = _______ [use g = 10 m s−2 ].

Q21.A particle starts from origin at t = 0 with a velocity 5ˆi m s−1 and moves in x −y plane under action of a force which produces a constant acceleration of + m s−2 . If the x-coordinate of the particle at that instant is (3ˆi 2ˆj) 84 m, then the speed of the particle at this time is √α m s−1 . The value of α is _______.