Practice Questions

Q73.During " S " estimation, 160 mg of an organic compound gives 466 mg of barium sulphate. The percentage of – Sulphur in the given compound is _______ %. (Given molar mass in gmol−1 of Ba : 137, S : 32, O : 16 )

Q73.When 81.0 g of aluminium is allowed to react with 128.0 g of oxygen gas, the mass of aluminium oxide produced in grams is_______ - (Nearest integer) Given : Molar mass of Al is 27.0 g mol−1 Molar mass of O is 16.0 g mol−1

Q73.Consider a complex reaction taking place in three steps with rate constants k1, k2 and k3 respectively. The overall rate constant k is given by the expression k = . If the activation energies of the three steps are √k1k3k2 60,30 and 10 kJ mol−1 respectively, then the overall energy of activation in kJmol−1 is … … . (Nearest integer)

Q73.Total number of molecules/species from following which will be paramagnetic is ______ O2, O+2 , O−2 , NO, NO2, CO, K2 [NiCl4], [Co(NH3)6]Cl3, K2 [Ni(CN)4]

Q73.The sum of sigma (σ) and pi (π) bonds in Hex-1,3-dien-5-yne is _______. Q74. 0.1 mole of compound ' S ' will weigh _______ g. (Given molar mass in gmol−1C : 12, H : 1, O : 16)

Q74.The bond dissociation enthalpy of X2ΔHbond calculated from the given data is kJmol−1 . (Nearest M+X−(s) →M+(g) + X−(g)ΔH∗lattice = 800 kJ mol−1 integer) M( s) →M( g)ΔH∘sub = 100 kJ mol−1 M( g) →M+(g) + e−(g)ΔHi = 500 kJ mol−1 X( g) + e−(g) →X−(g)ΔH∗eg = −300 kJ mol−1 M( s) + 12 X2( g) →M+X−(s)ΔH∘f = −400 kJ mol−1 [Given : M+X− is a pure ionic compound and X forms a diatomic molecule X2 in gaseous state] 2025 (23 Jan Shift 2) JEE Main Previous Year Paper

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.Quantitative analysis of an organic compound (X) shows following \% composition. C : 14.5% Cl : 64.46\% H: 1.8 \% (Empirical formula mass of the compound (X) is __________ ×10−1 (Given molar mass in gmol−1 of C : 12, H : 1, O : 16, Cl : 35.5 )

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)

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

Q74.Some CO2 gas was kept in a sealed container at a pressure of 1 atm and at 273 K . This entire amount of CO2 gas was later passed through an aqueous solution of Ca(OH)2 . The excess unreacted Ca(OH)2 was later neutralized with 0.1 M of 40 mL HCl . If the volume of the sealed container of CO2 was x, then x is ________ cm3 (nearest integer). [Given : The entire amount of CO2( g) reacted with exactly half the initial amount of Ca(OH)2 present in the aqueous solution.] 2025 (22 Jan Shift 1) JEE Main Previous Year Paper

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.Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with K4 [Fe(CN)6] is _____. Cu2+, Fe3+, Ba2+, Ca2+, NH+4 , Mg2+, Zn2+

Q74.In the Claisen-Schmidt reaction to prepare, dibenzalacetone from 5.3 g of benzaldehyde, a total of 3.51 g of product was obtained. The percentage yield in this reaction was ______ %.

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. 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.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 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.Total number of non bonded electrons present in NO2− ion based on Lewis theory is 2025 (29 Jan Shift 2) 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 complex of Ni2+ ion and dimethyl glyoxime contains ________ number of Hydrogen (H) atoms. 2025 (22 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.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.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

Q51.The total number of molccules with zero dipole moment among CH4, BF3, H2O, HF, NH3, CO2 and SO2 is ______.