NEET Chemistry Important & Repeated Questions 2027

1 gram of sodium hydroxide was treated with 25 mL of 0.75 M HCl solution, the mass of sodium hydroxide left unreacted is equal to: (1) 200 mg (2) 750 mg (3) 250 mg (4) Zero mg

Among the following, choose the ones with equal number of atoms. A. 212 g of Na₂CO₃ (s) [molar mass = 106 g] B. 248 g of Na₂O (s) [molar mass = 62 g] C. 240 g of NaOH (s) [molar mass = 40 g] D. 12 g of H₂ (g) [molar mass = 2 g] E. 220 g of CO₂ (g) [molar mass = 44 g]. Choose the correct answer from the options given below: (1) A, B, and C only (2) A, B, and D only (3) B, C, and D only (4) B, D, and E only

The ratio of the wavelengths of the light absorbed by a Hydrogen atom when it undergoes n = 2 -> n = 3 and n = 4 -> n = 6 transitions, respectively, is (1) 1/36 (2) 1/16 (3) 1/9 (4) 1/4

Match List I with List II. List I (Quantum Number): A. m_l B. m_s C. l D. n List II (Information provided): I. shape of orbital II. size of orbital III. orientation of orbital IV. orientation of spin of electron Choose the correct answer from the options given below: (1) A-II, B-I, C-IV, D-III (2) A-I, B-III, C-II, D-IV (3) A-III, B-IV, C-I, D-II (4) A-III, B-IV, C-II, D-I

Given below are two statements: Statement I: A hypothetical diatomic molecule with bond order zero is quite stable. Statement II: As bond order increases, the bond length increases. In the light of the above statements, choose the most appropriate answer from the options given below: (1) Both Statement I and Statement II are true (2) Both Statement I and Statement II are false (3) Statement I is true but Statement II is false (4) Statement I is false but Statement II is true

Match List I with List II. List I (Molecule): A. ethane B. ethene C. carbon molecule, C₂ D. ethyne List II (Number and types of bond/s between two carbon atoms): I. one σ-bond and two π-bonds II. two π-bonds III. one σ-bond IV. one σ-bond and one π-bond Choose the correct answer from the options given below: (1) A-III, B-IV, C-I, D-II (2) A-I, B-IV, C-II, D-III (3) A-IV, B-III, C-II, D-I (4) A-III, B-IV, C-II, D-I

Match List I with List II. List I (Compound): A. NH₃ B. BrF₅ C. XeF₄ D. SF₆ List II (Shape/geometry): I. Trigonal Pyramidal II. Square Planar III. Octahedral IV. Square Pyramidal Choose the correct answer from the options given below: (1) A-II, B-III, C-IV, D-I (2) A-I, B-IV, C-II, D-III (3) A-II, B-IV, C-III, D-I (4) A-III, B-IV, C-I, D-II

The work done during reversible isothermal expansion of one mole of hydrogen gas at 25°C from pressure of 20 atmosphere to 10 atmosphere is: (Given R = 2.0 cal K^-1 mol^-1) (1) 100 calories (2) 0 calorie (3) -413.14 calories (4) 413.14 calories

Which of the following aqueous solution will exhibit highest boiling point? (1) 0.01M Urea (2) 0.01M KNO₃ (3) 0.01M Na₂SO₄ (4) 0.015M C₆H₁₂O₆

For the reaction A(g) <=> 2B(g), the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500, at 1000 K. [Given: R = 0.0831 L atm mol^-1 K^-1] K_p for the reaction at 1000 K is (1) 83.1 (2) 2.077 x 10⁵ (3) 0.033 (4) 0.021

Consider the following reaction in a sealed vessel at equilibrium with concentrations of N₂ = 3.0×10^-3 M, O₂ = 4.2×10^-3 M and NO = 2.8×10^-3 M. 2 NO_(g) ⇌ N₂(g) + O₂(g) If 0.1 mol L^-1 of NO_(g) is taken in a closed vessel, what will be degree of dissociation (α) of NO_(g) at equilibrium? (1) 0.717 (2) 0.00889 (3) 0.0889 (4) 0.8889

Consider the following compounds: KO₂, H₂O₂ and H₂SO₄. The oxidation states of the underlined elements (O, O, S) in them are, respectively, (1) +1, -1, and +6 (2) +2, -2, and +6 (3) +1, -2, and +4 (4) +4, -4, and +6

If the molar conductivity (Lambda_m) of a 0.050 mol L^-1 solution of a monobasic weak acid is 90 S cm² mol^-1, its extent (degree) of dissociation will be [Assume Lambda_+⁰ = 349.6 S cm² mol^-1 and Lambda_-⁰ = 50.4 S cm² mol^-1.] (1) 0.115 (2) 0.125 (3) 0.225 (4) 0.215

Match List I with List II. List I (Conversion): A. 1 mol of H₂O to O₂ B. 1 mol of MnO₄^- to Mn²⁺ C. 1.5 mol of Ca from molten CaCl₂ D. 1 mol FeO to Fe₂O₃ List II (Number of Faraday required): I. 3F II. 2F III. 1F IV. 5F Choose the correct answer from the options given below: (1) A-III, B-IV, C-II, D-I (2) A-II, B-IV, C-I, D-III (3) A-III, B-IV, C-I, D-II (4) A-II, B-III, C-I, D-IV

At 298 K, the standard electrode potentials of Cu²⁺/Cu, Zn²⁺/Zn, Fe²⁺/Fe and Ag^+/Ag are 0.34 V, -0.76 V, -0.44 V and 0.80 V, respectively. On the basis of standard electrode potential, predict which of the following reaction can not occur? (1) 2CuSO₄(aq) + 2Ag(s) -> 2Cu(s) + Ag₂SO₄(aq) (2) CuSO₄(aq) + Zn(s) -> ZnSO₄(aq) + Cu(s) (3) CuSO₄(aq) + Fe(s) -> FeSO₄(aq) + Cu(s) (4) FeSO₄(aq) + Zn(s) -> ZnSO₄(aq) + Fe(s)

If the half-life (t₁/2) for a first order reaction is 1 minute, then the time required for 99.9% completion of the reaction is closest to (1) 2 minutes (2) 4 minutes (3) 5 minutes (4) 10 minutes

Activation energy of any chemical reaction can be calculated if one knows the value of: (1) rate constant at two different temperatures. (2) rate constant at standard temperature. (3) probability of collision. (4) orientation of reactant molecules during collision.

Arrange the following elements in increasing order of first ionization enthalpy: Li, Be, B, C, N Choose the correct answer from the options given below: (1) Li < Be < N < B < C (2) Li < Be < B < C < N (3) Li < B < Be < C < N (4) Li < Be < C < B < N

Given below are two statements: Statement I: The boiling point of hydrides of Group 16 elements follow the order H₂O > H₂Te > H₂Se > H₂S. Statement II: On the basis of molecular mass, H₂O is expected to have lower boiling point than the other members of the group but due to the presence of extensive H-bonding in H₂O, it has higher boiling point. In the light of the above statements, choose the correct answer from the options given below: (1) Statement I is false but Statement II is true. (2) Both Statement I and Statement II are true. (3) Both Statement I and Statement II are false. (4) Statement I is true but Statement II is false.

Match List-I with List-II: List-I: A. Coke, B. Diamond, C. Fullerene, D. Graphite List-II: I. Carbon atoms are sp³ hybridised. II. Used as a dry lubricant. III. Used as a reducing agent. IV. Cage like molecules Choose the correct answer from the options given below: (1) A-III, B-IV, C-I, D-II (2) A-II, B-IV, C-I, D-III (3) A-IV, B-I, C-II, D-III (4) A-III, B-I, C-IV, D-II

Given below are two statements: Statement I: Ferromagnetism is considered as an extreme form of paramagnetism. Statement II: The number of unpaired electrons in a Cr²⁺ ion (Z = 24) is the same as that of a Nd³⁺ ion (Z = 60). In the light of the above statements, choose the correct answer from the options given below: (1) Both Statement I and Statement II are true (2) Both Statement I and Statement II are false (3) Statement I is true but Statement II is false (4) Statement I is false but Statement II is true

Which of the following are paramagnetic? A. [NiCl₄]^2- B. Ni(CO)₄ C. [Ni(CN)₄]^2- D. [Ni(H₂O)₆]²⁺ E. Ni(PPh₃)₄. Choose the correct answer from the options given below: (1) A and C only (2) B and E only (3) A and D only (4) A, D and E only

The correct order of the wavelength of light absorbed by the following complexes is. A. [Co(NH₃)₆]³⁺ B. [Co(CN)₆]^3- C. [Cu(H₂O)₄]²⁺ D. [Ti(H₂O)₆]³⁺. Choose the correct answer from the options given below: (1) B < D < A < C (2) B < A < D < C (3) C < D < A < B (4) C < A < D < B

Given below are two statements: Statement I: [Co(NH₃)₆]³⁺ is a homoleptic complex whereas [Co(NH₃)₄Cl₂]^+ is a heteroleptic complex. Statement II: Complex [Co(NH₃)₆]³⁺ has only one kind of ligands but [Co(NH₃)₄Cl₂]^+ has more than one kind of ligands. In the light of the above statements, choose the correct answer from the options given below: (1) Statement I is false but Statement II is true. (2) Both Statement I and Statement II are true. (3) Both Statement I and Statement II are false. (4) Statement I is true but Statement II is false.

Match List I with List II. List I (Mixture): A. CHCl₃ + C₆H₅NH₂ B. Crude oil in petroleum industry C. Glycerol from spent-lye D. Aniline - water. List II (Method of Separation): I. Distillation under reduced pressure II. Steam distillation III. Fractional distillation IV. Simple distillation. Choose the correct answer from the options given below: (1) A-IV, B-III, C-I, D-II (2) A-IV, B-III, C-II, D-I (3) A-III, B-IV, C-I, D-II (4) A-III, B-IV, C-II, D-I

Which one of the following reactions does NOT belong to "Lassaigne's test"? (1) Na + C + N -heat-> NaCN (2) 2Na + S -heat-> Na₂S (3) Na + X -heat-> NaX (4) 2CuO + C -heat-> 2Cu + CO₂

For the given reaction: (cyclohexyl)-CH=CH-(cyclohexyl) --KMnO₄/H^+--> 'P' (major product). 'P' is: (the four options are structures shown in the figure) (1) cyclohexyl-CO-CO-cyclohexyl (diketone) (2) cyclohexanecarbaldehyde (cyclohexyl-CHO) (3) cyclohexanecarboxylic acid (cyclohexyl-COOH) (4) cyclohexyl-CH(OH)-CH(OH)-cyclohexyl (vicinal diol)

Consider the following compounds/species: i. naphthalene ii. cyclopentadienyl anion iii. cyclobutadiene dication (square four-membered ring) iv. cyclopropenyl anion (three-membered ring with negative charge) v. cyclopropenyl cation (three-membered ring with positive charge) vi. cyclooctatetraene vii. anthracene The number of compounds/species which obey Huckel's rule is ________. (1) 5 (2) 4 (3) 6 (4) 2

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): 1-iodo compound undergoes S_N2 reaction faster than the corresponding 1-chloro compound. Reason (R): Iodine is a better leaving group because of its large size. In the light of the above statements, choose the correct answer from the options given below: (1) Both A and R are true and R is the correct explanation of A (2) Both A and R are true but R is not the correct explanation of A (3) A is true but R is false (4) A is false but R is true

Identify the suitable reagent for the following conversion. Methyl benzoate (Ph-CO-OCH₃) -> benzaldehyde (Ph-CHO). (1) (i) LiAlH₄, (ii) H^+/H₂O (2) (i) AlH(iBu)₂ (ii) H₂O (3) (i) NaBH₄, (ii) H^+/H₂O (4) H₂ / Pd-BaSO₄

The correct order of decreasing acidity of the following aliphatic acids is (1) (CH₃)₃CCOOH > (CH₃)₂CHCOOH > CH₃COOH > HCOOH (2) CH₃COOH > (CH₃)₂CHCOOH > (CH₃)₃CCOOH > HCOOH (3) HCOOH > CH₃COOH > (CH₃)₂CHCOOH > (CH₃)₃CCOOH (4) HCOOH > (CH₃)₃CCOOH > (CH₃)₂CHCOOH > CH₃COOH

The major product of the following reaction is: PhCO-CH_2-CH_2-CN (3-oxo-3-phenylpropanenitrile chain, i.e. an aryl ketone bearing a nitrile) treated with (i) CH₃MgBr (excess) (ii) H₃O^+. (1) tertiary alcohol from the ketone with CN retained: Ph-C(CH₃)(OH)-CH_2-CN (2) Ph-C(CH₃)(OH)-CH_2-CH_2-CO-CH₃ (alcohol from ketone + methyl ketone from nitrile) (3) diol: Ph-C(CH₃)(OH)-CH_2-C(OH)(CH₃)₂ (4) diketone: Ph-CO-CH_2-CH_2-CO-CH₃

Fehling's solution 'A' is: (1) aqueous sodium citrate (2) aqueous copper sulphate (3) alkaline copper sulphate (4) alkaline solution of sodium potassium tartrate (Rochelle's salt)

Which one of the following alcohols reacts instantaneously with Lucas reagent? (1) (CH₃)₃C-OH (2) CH_3-CH_2-CH_2-CH₂OH (3) CH_3-CH_2-CH(OH)-CH₃ (4) (CH₃)₂CH-CH₂OH

Complete the following reaction: Cyclohexanone (>C=O) --HCN--> [A] cyanohydrin (ring carbon bearing -OH and -CN) --conc. H₂SO₄, delta--> [C] [C] is ________. (1) cyclohexene ring bearing -COOH (an alpha,beta-unsaturated carboxylic acid; 1-cyclohexene carboxylic acid) (2) cyclohexane ring bearing -OH (3) cyclohexane ring bearing -COOH (4) cyclohexene ring bearing -CHO

Predict the major product 'P' in the following sequence of reactions - 1-methylcyclopentene reacting with (i) HBr, benzoyl peroxide (ii) KCN (iii) Na(Hg)/C₂H₅OH -> P (Major). (1) 2-methylcyclopentyl-CH₂NH₂ (2) 1-methylcyclopentyl-CH₂NH₂ (3) 2-methylcyclopentyl-NC (4) 1-methylcyclopentyl bearing NC and CH₃

Given below are two statements: Statement I: Benzenediazonium salt is prepared by the reaction of aniline with nitrous acid at 273-278 K. It decomposes easily in the dry state. Statement II: Insertion of iodine into the benzene ring is difficult and hence iodobenzene is prepared through the reaction of benzenediazonium salt with KI. In the light of the above statements, choose the most appropriate answer from the options given below: (1) Both Statement I and Statement II are correct (2) Both Statement I and Statement II are incorrect (3) Statement I is correct but Statement II is incorrect (4) Statement I is incorrect but Statement II is correct

Sugar 'X': A. is found in honey. B. is a keto sugar. C. exists in alpha and beta - anomeric forms. D. is laevorotatory. 'X' is: (1) D-Glucose (2) D-Fructose (3) Maltose (4) Sucrose

Match List I with List II. List I (Ion): A. Co²⁺ B. Mg²⁺ C. Pb²⁺ D. Al³⁺. List II (Group Number in Cation Analysis): I. Group-I II. Group-III III. Group-IV IV. Group-VI. Choose the correct answer from the options given below: (1) A-III, B-IV, C-II, D-I (2) A-III, B-IV, C-I, D-II (3) A-III, B-II, C-IV, D-I (4) A-III, B-II, C-I, D-IV