#neet
- The correct order of decreasing basic strength of the given amines is : Answer: 3. N-ethylethanamine > ethanamine > N-methylaniline > benzenamine Key idea: aliphatic amines are stronger bases than aromatic ones,... 1
- Among the following, choose the ones with equal number of atoms.A. 212 g of Na_2CO_3 (s) [molar mass = 106 g]B. 248 g of Na_2O (s) [molar mass = 62 g]C. 240 g of NaOH (s) [molar mass = 40 g]D. 12 g of H_2 (g) [molar mass = 2 g]E. 220 g of CO_2(g) [mo… Answer: 2. A, B, and D only Key idea: number of atoms = moles × atoms per formula unit × N_A . A: 212 g = 2 mol × 6 = 12 mol atoms. B: 248 g... 1
- Match List I with List II.List I (Name of Vitamin): A. Vitamin B_12 B. Vitamin D C. Vitamin B_2 D. Vitamin B_6List II (Deficiency disease): I. Cheilosis II. Convulsions III. Rickets IV. Pernicious anaemiaChoose the correct answer from the options giv… Answer: 2. A-IV, B-III, C-I, D-II Vitamin mathrmB₁₂ : pernicious anaemia (IV). Vitamin D: rickets (III). Vitamin B₂ (riboflavin): cheilosis... 1
- The correct order of decreasing acidity of the following aliphatic acids is : Answer: 3. HCOOH > CH₃COOH > (CH₃)₂CHCOOH > (CH₃)₃CCOOH Key idea: alkyl groups are electron-donating (+I) and destabilise the carboxylate io... 1
- 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 Cr^2+ ion (Z = 24) is the same as that of a Nd^3+ ion (Z = 60).In the light of the abo… Answer: 3. Statement I is true but Statement II is false Statement I is true: ferromagnetism is the extreme form of paramagnetism (domains a... 1
- Match List I with List IIList I (Mixture): A. CHCl_3 + C_6H_5NH_2 B. Crude oil in petroleum industry C. Glycerol from spent-lye D. Aniline - waterList II (Method of Separation): I. Distillation under reduced pressure II. Steam distillation III. Fract… Answer: 1. A-IV, B-III, C-I, D-II CHCl₃ + aniline: boiling points well apart (334 K vs 457 K), simple distillation (IV). Crude oil: fraction... 1
- 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 Answer: 3. 0.033 Key idea: K_c=k_f/k_b and K_p=K_c(RT)^(Δ n) . k_b=2500 k_f , so K_c=1/2500=4×10⁻⁴ . Δ n=2-1=1 ; RT=0.0831×1000=83.1 . K_p=4... 1
- 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 a… Answer: 1. Both Statement I and Statement II are correct Statement I is correct: diazotisation of aniline with NaNO₂/HCl is done at 273-278... 1
- How many products (including stereoisomers) are expected from monochlorination of the following compound?(CH_3)_2CH-CH_2-CH_3 Answer: 4. 6 Key idea: count the distinct kinds of hydrogen in 2-methylbutane, then count stereoisomers. Two equivalent CH₃ on C-2: 1-chloro... 1
- Among the given compounds I-III, the correct order of bond dissociation energy of C-H bond marked with * is : Answer: 1. II > I > III Key idea: the more s-character in the carbon, and the less stable the radical left behind, the stronger the C-H bond... 1
- Which one of the following compounds does not decolourize bromine water? Answer: 1. cyclohexane Key idea: bromine water is decolourised by alkenes (addition) and by activated aromatics (substitution). Styrene: C=C... 1
- The major product of the following reaction is :Reactant: Ph-CO-CH2CH2-CN; (i) CH_3MgBr (excess); (ii) H_3O^+ Answer: 2. structure (2) Key idea: Grignard reagent adds to both the ketone and the nitrile, but the nitrile adduct is hydrolysed to a keton... 1
- Which of the following aqueous solution will exhibit highest boiling point? Answer: 3. 0.01M Na₂SO₄ Key idea: elevation of boiling point depends on i× c . Urea: 1×0.01=0.01 . KNO₃ : 2×0.01=0.02 . Na₂SO₄ : 3×0.01=0.03... 1
- Match List - I with List - IIList-I: A. Haber process B. Wacker oxidation C. Wilkinson catalyst D. Ziegler catalystList-II: I. Fe catalyst II. PdCl_2 III. [(PPh_3)_3RhCl] IV. TiCl_4 with Al(CH_3)_3Choose the correct answer from the options given belo… Answer: 3. A-I, B-II, C-III, D-IV Haber process: Fe catalyst (I). Wacker oxidation (ethene to ethanal): PdCl₂ (II). Wilkinson catalyst: [(PP... 1
- 5 moles of liquid X and 10 moles of liquid Y make a solution having a vapour pressure of 70 torr. The vapour pressures of pure X and Y are 63 torr and 78 torr respectively. Which of the following is true regarding the described solution? Answer: 2. The solution shows negative deviation. Key idea: compare the observed vapour pressure with the Raoult's law value. x_X=5/15=1/3 ,... 1
- Sugar 'X'A. is found in honey.B. is a keto sugar.C. exists in α and β - anomeric forms.D. is laevorotatory.'X' is : Answer: 2. D-Fructose Key idea: match each property. D-Fructose is present in honey, is a keto sugar (ketohexose), exists as α and β anomers... 1
- Identify the suitable reagent for the following conversion.Methyl benzoate (Ph-COOCH3) → benzaldehyde (Ph-CHO) Answer: 2. (i) AlH(iBu)₂ (ii) H₂O Key idea: partial reduction of an ester to an aldehyde needs DIBAL-H at low temperature. AlH(i-Bu)₂ follow... 1
- Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : (primary alkyl iodide drawn as zig-zag chain ending in I) undergoes S_N2 reaction faster than (the corresponding alkyl chloride,… Answer: 1. Both A and R are true and R is the correct explanation of A Key idea: in S_N2 the rate depends on how easily the leaving group de... 1
- The standard heat of formation, in kcal/mol of Ba^2+ is :[Given : standard heat of formation of SO_4^2- ion (aq) = -216 kcal/mol, standard heat of crystallisation of BaSO_4(s) = -4.5 kcal/mol, standard heat of formation of BaSO_4(s) = -349 kcal/mol] Answer: 1. -128.5 Key idea: mathrmBa²⁺(aq)+SO₄²⁻(aq)→ BaSO₄(s) has Δ H=-4.5 kcal (crystallisation). Δ H_f(BaSO₄)=Δ H_f(mathrmBa²⁺)+Δ H_f(mat... 1
- Total number of possible isomers (both structural as well as stereoisomers) of cyclic ethers of molecular formula C_4H_8O is : Answer: 3. 10 Key idea: list all rings of formula C₄H₈O containing O, and count enantiomers/cis-trans. Oxolane (THF): 1. Oxetane with a meth... 1
- Identify the correct orders against the property mentioned :A. H_2O > NH_3 > CHCl_3 - dipole momentB. XeF_4 > XeO_3 > XeF_2 - number of lone pairs on central atomC. O-H > C-H > N-O - bond lengthD. N_2 > O_2 > H_2 - bond enthalpyChoose the correct ans… Answer: 1. A, D only A true: H₂O (1.85 D) > NH₃ (1.47 D) > CHCl₃ (1.04 D). B false: lone pairs on Xe are XeF₄ = 2, XeO₃ = 1, XeF₂ = 3, so th... 1
- A full wave rectifier circuit with diodes (D_1) and (D_2) is shown in the figure. If input supply voltage V_in = 220(100π t) volt, then at t = 15 msec Answer: 1. D₁ is forward biased, D₂ is reverse biased or 2. D₁ is reverse biased, D₂ is forward biased Key idea: in a centre-tapped full-wav... 1
- Two gases A and B are filled at the same pressure in separate cylinders with movable pistons of radius r_A and r_B, respectively. On supplying an equal amount of heat to both the systems reversibly under constant pressure, the pistons of gas A and B… Answer: 2. 3/4 Key idea: at constant pressure, Q=Δ U+W with W=pΔ V . The heat supplied and Δ U are the same for both gases, so W is equal. W... 1
- A physical quantity P is related to four observations a, b, c and d as follows:P = a^3b^2 / c√(d)The percentage errors of measurement in a, b, c and d are 1%, 3%, 2%, and 4% respectively. The percentage error in the quantity P is Answer: 3. 13% Key idea: for P=a³b²/csqrt d , the maximum percentage error is the sum of (power × percentage error) of each quantity. Δ P/P×... 1