Practice Questions

Q72.A compound ' X′ absorbs 2 moles of hydrogen and ' X′ upon oxidation with KMnO4 ∣H+ gives The total number of σ bonds present in the compound ' X′ is______

Q72.The observed and normal molar masses of compound MX2 are 65.6 and 164 respectively. The percent degree of ionisation of MX2 is … … %. (Nearest integer)

Q72.The molarity of a 70% (mass / mass) aqueous solution of a monobasic acid (X) is __________ ×10−1 M(Nearest integer) [Given: Density of aqueous solution of (X) is 1.25 g mL−1 Molar mass of the acid is 70 g mol−1 ] 2025 (28 Jan Shift 1) JEE Main Previous Year Paper

Q72.Isomeric hydrocarbons → negative Baeyer's test (Molecular formula C9H12 ) The total number of isomers from above with four different non-aliphatic substitution sites is -

Q72.Given below are some nitrogen containing compounds ∣∣∣ 2025 (29 Jan Shift 1) JEE Main Previous Year Paper Each of them is treated with HCl separately. 1.0 g of the most basic compound will consume _______ mg of HCl. (Given molar mass in gmol−1C : 12, H : 1, O : 16, Cl : 35.5)

Q72. A → B The molecule A changes into its isomeric form B by following a first order kinetics at a temperature of 1000 K . If the energy barrier with respect to reactant energy for such isomeric transformation is 191.48 kJ mol−1 and the frequency factor is 1020 , the time required for 50% molecules of A to become B is _________ picoseconds (nearest integer). [R = 8.314 J K−1 mol−1]

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)

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.Consider the following sequence of reactions: 11.25 mg of chlorobenzene will produce __________ ×10−1mg of product B . (Consider the reactions result in complete conversion.) [Given molar mass of C, H, O, N and Cl as 12, 1, 16, 14 and 35.5 g mol−1 respectively]

Q73.Consider the following low-spin complexes K3 [Co(NO2)6], K4 [Fe(CN)6], K3 [Fe(CN)6], Cuu2 [Fe(CN)6] and Zn2 [Fe(CN)6] The sum of the spin-only magnetic moment values of complexes having yellow colour is. _____ B.M. (answer in nearest integer)

Q73.Consider the following cases of standard enthalpy of reaction (ΔH∘r in kJmol−1) 7 C2H6( g) + O2( g) →2CO2( g) + 3H2O(l)ΔH∘1 = −1550 2 C (graphite) + O2( g) →CO2( g) ΔH∘2 = −393.5 The magnitude of ΔH∘fC2H6( g) is _______ 1 H2( g) + O2( g) →H2O(l) ΔH∘3 = −286 2 kJmol−1 (Nearest integer).

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.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. Consider the following sequence of reactions : Molar mass of the product formed (A) is _______ gmol−1 .

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 )

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 ______ %.

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 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.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.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.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.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.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

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