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.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.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.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.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.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

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.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.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.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.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.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.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 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

Q31.Combustion of glucose (C6H12O6) produces CO2 and water. The amount of oxygen (in g) required for the complete combustion of 900 g of glucose is : [Molar mass of glucose in gmol−1 = 180 ] (1) 480 (2) 800 (3) 960 (4) 32

Q31.Compare the energies of following sets of quantum numbers for multielectron system. (A) n = 4, 1 = 1 (B) n = 4, l = 2 (C) n = 3, 1 = 1 (D) n = 3, 1 = 2 (E) n = 4, 1 = 0 Choose the correct answer from the options given below : (1) (B) > (A) > (C) > (E) > (D) (2) (E) < ( C ) < (D) < ( A ) < ( B ) (3) (E) > ( C ) > ( A ) > ( D ) > (B) (4) (C) < (E) < (D) < (A) < (B)

Q31.A sample of CaCO3 and MgCO3 weighed 2 .21 g is ignited to constant weight of 1 .152 g. The composition of the mixture is: (Given molar mass in g mol−1, CaCO3: 100, MgCO3: 84) (1) 1 .187 𝑔 𝐶𝑎𝐶𝑂3 + 1 .023 𝑔 𝑀𝑔𝐶𝑂3 (2) 1 .023 𝑔 𝐶𝑎𝐶𝑂3 + 1 .023 𝑔 𝑀𝑔𝐶𝑂3 (3) 1 .187 𝑔 𝐶𝑎𝐶𝑂3 + 1 .187 𝑔 𝑀𝑔𝐶𝑂3 (4) 1 .023 𝑔 𝐶𝑎𝐶𝑂3 + 1 .187 𝑔 𝑀𝑔𝐶𝑂3

Q31.Match List I with List II Choose the correct answer from the options given below :- (1) A-II, B-III, C-I, D-IV (2) A-I, B-III, C-II, D-IV (3) A-II, B-IV, C-III, D-I (4) A-I, B-II, C-III, D-IV

Q31.Given below are two statements: Statement - I: Along the period, the chemical reactivity of the element gradually increases from group 1 to group 18 . Statement - II: The nature of oxides formed by group 1 element is basic while that of group 17 elements is acidic. In the the light above statements, choose the most appropriate from the questions given below: (1) Both statement I and Statement II are true. (2) Statement I is true but Statement II is False. (3) Statement I is false but Statement II is true. (4) Both Statement I and Statement II is false.

Q31.Identify the correct statements about p-block elements and their compounds. (A) Non metals have higher electronegativity than metals. (B) Non metals have lower ionisation enthalpy than metals. (C) Compounds formed between highly reactive nonmetals and highly reactive metals are generally ionic. (D) The non-metal oxides are generally basic in nature. (E) The metal oxides are generally acidic or neutral in nature. Choose the correct answer from the options given below : (1) (B) and (D) only (2) (A) and (C) only (3) (D) and (E) only (4) (B) and (E) only

Q31.Given below are two statements: Statement-I: The orbitals having same energy are called as degenerate orbitals. Statement-II: In hydrogen atom, 3p and 3 d orbitals are not degenerate orbitals. In the light of the above statements, choose the most appropriate answer from the options given (1) Statement-I is true but Statement-II is false (2) Both Statement-I and Statement-II are true. (3) Both Statement-I and Statement-II are false (4) Statement-I is false but Statement-II is true

Q31.The correct sequence of electron gain enthalpy of the elements listed below is A. Ar B. Br C. F D. S Choose the most appropriate from the options given below: (1) C > B > D > A (2) A > D > B > C (3) A > D > C > B (4) D > C > B > A

Q31.The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency ' A ' ×1012 hertz and that has a radiant intensity in that direction of ′ 1B′ watt per steradian. 'A' and 'B' are respectively (1) 540 and 683 (2) 450 and 683 (3) 450 and 1 (4) 540 and 1 683 683