NEET UG

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Match List - I with List - II.List - I : (a) benzene [Anhyd. AlCl_3/CuCl]CO,\ HCl (b) R-CO-CH_3 + NaOX → (c) R-CH_2-OH + R'COOH Conc. H_2SO_4 (d) R-CH_2COOH [(ii) H_2O](i) X_2/Red PList - II : (i) Hell-Volhard-Zelinsky reaction (ii) Gattermann-Koch r… Answer: 4. (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i) Key idea: match each reaction with its name. (a) benzene + CO, HCl, anhydrous AlCl₃ /CuCl:... Aldehydes and ketones: HCN, NH3 derivatives, Grignard, oxidation, reduction (Wolff-Kishner, Clemmensen) 1 answer
The molar conductivity of 0.007 M acetic acid is 20 S cm^2 mol^-1. What is the dissociation constant of acetic acid ? Choose the correct option.^°_H^+ = 350 S cm^2 mol^-1, ^°_CH_3COO^- = 50 S cm^2 mol^-1 Answer: 3. 1.75×10⁻⁵ mol L ⁻¹ Key idea: α=Lambda_m/Lambda^°_m , and K_a=Cα²/1-α≈ Cα² . Lambda^°=350+50=400 ; α=20/400=0.05 . K_a≈0.007×(0.05... Conductance, molar conductivity and its variation with concentration 1 answer
The correct option for the value of vapour pressure of a solution at 45^° C with benzene to octane in molar ratio 3 : 2 is :[At 45^° C vapour pressure of benzene is 280 mm Hg and that of octane is 420 mm Hg. Assume Ideal gas] Answer: 3. 336 mm of Hg Key idea: Raoult's law for an ideal solution: P=x₁P₁^°+x₂P₂^° . x_benzene=3/5=0.6 , x_octane=2/5=0.4 . P=0.6(280)+0.... Vapour pressure and Raoult's law 1 answer
Tritium, a radioactive isotope of hydrogen, emits which of the following particles ? Answer: 1. Beta ( β^- ) Key idea: tritium ( ³₁H ) is a beta emitter. ³₁H→³₂He+β^-+barν : a neutron changes into a proton, emitting a β^- par... Atomic and molecular masses, mole concept, molar mass 1 answer
Choose the correct option for the total pressure (in atm.) in a mixture of 4 g O_2 and 2 g H_2 confined in a total volume of one litre at 0^° C is :[Given R=0.082 L atm mol^-1K^-1, T=273 K] Answer: 3. 25.18 Key idea: PV=nRT with total moles of gas. n_(O_2)=4/32=0.125 ; n_(H_2)=2/2=1 ; total = 1.125 mol. P=nRT/V=1.125×0.082×273/1... Atomic and molecular masses, mole concept, molar mass 1 answer
Match List - I with List - II.List - I : (a) 2SO_2(g) + O_2(g) → 2SO_3(g) (b) HOCl(g) h OH + Cl (c) CaCO_3 + H_2SO_4 → CaSO_4 + H_2O + CO_2 (d) NO_2(g) h NO(g) + O(g)List - II : (i) Acid rain (ii) Smog (iii) Ozone depletion (iv) Tropospheric pollutio… Answer: 3. (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii) Key idea: identify each reaction with its environmental context. (a) SO₂ oxidised to SO₃ i... Types of organic reactions 1 answer
A particular station of All India Radio, New Delhi, broadcasts on a frequency of 1,368 kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is : [speed of light, c=3.0×10^8 ms^-1] Answer: 1. 219.3 m Key idea: λ=c/ν . ν=1368\ kHz=1.368×10⁶\ mathrms⁻¹ λ=3.0×10⁸/1.368×10⁶=219.3\ m . Electromagnetic radiation, photoelectric effect, hydrogen spectrum 1 answer
Given below are two statements :Statement I : Aspirin and Paracetamol belong to the class of narcotic analgesics.Statement II : Morphine and Heroin are non-narcotic analgesics.In the light of the above statements, choose the correct answer from the o… Answer: 2. Both Statement I and Statement II are false. Key idea: aspirin and paracetamol are non-narcotic analgesics; morphine and heroin a... Hormones (general introduction) 1 answer
Right option for the number of tetrahedral and octahedral voids in hexagonal primitive unit cell are : Answer: 4. 12, 6 Key idea: in a close-packed structure with n atoms per cell, there are n octahedral voids and 2n tetrahedral voids. A hexag... Ionic bonding and lattice enthalpy 1 answer
The structures of beryllium chloride in solid state and vapour phase, are : Answer: 1. Chain and dimer, respectively Key idea: BeCl₂ is electron deficient and completes its octet by bridging. In the solid state it fo... VSEPR theory and shapes of molecules 1 answer
Match List - I with List - II.List - I : (a) PCl_5 (b) SF_6 (c) BrF_5 (d) BF_3List - II : (i) Square pyramidal (ii) Trigonal planar (iii) Octahedral (iv) Trigonal bipyramidalChoose the correct answer from the options given below. Answer: 1. (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii) Key idea: use VSEPR to find shapes. PCl₅ : 5 bond pairs, trigonal bipyramidal (iv) SF₆ : 6... VSEPR theory and shapes of molecules 1 answer
Statement I : Acid strength increases in the order given as HF << HCl << HBr << HI.Statement II : As the size of the elements F, Cl, Br, I increases down the group, the bond strength of HF, HCl, HBr and HI decreases and so the acid strength increases… Answer: 1. Both Statement I and Statement II are true. Key idea: acid strength of hydrogen halides depends on the H-X bond strength. Down th... Valence, oxidation states and chemical reactivity 1 answer
Ethylene diaminetetraacetate (EDTA) ion is : Answer: 1. Hexadentate ligand with four "O" and two "N" donor atoms Key idea: EDTA ⁴⁻ is a hexadentate ligand. It has two nitrogen donor ato... Werner's theory, ligands, coordination number, denticity, chelation 1 answer
Zr (Z=40) and Hf (Z=72) have similar atomic and ionic radii because of : Answer: 3. lanthanoid contraction Key idea: lanthanoid contraction. Between Zr (4d) and Hf (5d) come the 14 lanthanoids, whose poor shieldin... Lanthanoids and lanthanoid contraction 1 answer
The maximum temperature that can be achieved in blast furnace is : Answer: 2. upto 2200 K Key idea: this is a recall fact for iron extraction. In the blast furnace the temperature rises from about 500 K at t... Transition elements: configuration, occurrence and characteristics 1 answer
The pK_b of dimethylamine and pK_a of acetic acid are 3.27 and 4.77 respectively at T (K). The correct option for the pH of dimethylammonium acetate solution is : Answer: 3. 7.75 Key idea: for a salt of a weak acid and a weak base, pH=7+1/2(pK_a-pK_b) . pH=7+1/2(4.77-3.27)=7+0.75=7.75 . Common ion effect, hydrolysis of salts 1 answer
Dihedral angle of least stable conformer of ethane is : Answer: 4. 0^° Key idea: the eclipsed conformation of ethane has the highest torsional strain, so it is least stable. In the eclipsed form t... Alkanes: conformations, halogenation mechanism 1 answer
The correct sequence of bond enthalpy of 'C–X' bond is : Answer: 2. CH₃-F > CH₃-Cl > CH₃-Br > CH₃-I Key idea: bond enthalpy decreases as the halogen gets larger (longer, weaker C-X bond). Bond leng... Nature of C-X bond 1 answer
Identify the compound that will react with Hinsberg's reagent to give a solid which dissolves in alkali. Answer: 3. CH₃CH₂-ddotNH₂ Key idea: Hinsberg's reagent (benzenesulphonyl chloride) reacts with primary and secondary amines; the sulphonamid... Identification of 1/2/3 amines 1 answer
What is the IUPAC name of the organic compound formed in the following chemical reaction ?Acetone [(ii) H_2O, H^+](i) C_2H_5MgBr,\ dry Ether Product Answer: 4. 2-methyl butan-2-ol Key idea: a Grignard reagent adds to a ketone to give a tertiary alcohol. mathrm(CH₃)₂C=O+C₂H₅MgBr→(CH₃)₂C(C₂... Aldehydes and ketones: HCN, NH3 derivatives, Grignard, oxidation, reduction (Wolff-Kishner, Clemmensen) 1 answer
An organic compound contains 78% (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is : [Atomic wt. of C is 12, H is 1] Answer: 3. CH₃ Key idea: divide percentage by atomic mass, then take the simplest ratio. C: 78/12=6.5 ; H: 22/1=22 . Ratio H : C = 22/6.5≈3.... Empirical and molecular formula calculations 1 answer
The molar conductance of NaCl, HCl and CH_3COONa at infinite dilution are 126.45, 426.16 and 91.0 S cm^2 mol^-1 respectively. The molar conductance of CH_3COOH at infinite dilution is. Choose the right option for your answer. Answer: 2. 390.71 S cm ² mol ⁻¹ Key idea: Kohlrausch's law of independent migration of ions. Lambda^°(CH₃COOH)=Lambda^°(CH₃COONa)+Lambda^°(H... Kohlrausch's law and applications 1 answer
Which of the following reactions is the metal displacement reaction ? Choose the right option. Answer: 2. Cr₂O₃ + 2Al xrightarrowΔ Al₂O₃ + 2Cr Key idea: a metal displacement reaction is one where a more reactive metal displaces a less... Oxidation and reduction, oxidation number 1 answer
The following solutions were prepared by dissolving 10 g of glucose (C_6H_12O_6) in 250 ml of water (P_1), 10 g of urea (CH_4N_2O) in 250 ml of water (P_2) and 10 g of sucrose (C_12H_22O_11) in 250 ml of water (P_3). The right option for the decreasi… Answer: 1. P₂ > P₁ > P₃ Key idea: for equal mass in equal volume, osmotic pressure π=CRT is proportional to moles, i.e. inversely proportion... Colligative properties 1 answer

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