NEET UG

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On heating, some solid substances change from solid to vapour state without passing through liquid state. The technique used for the purification of such solid substances based on the above principle is known as Answer: 3. Sublimation Key idea: sublimation is the conversion of solid directly into vapour. Solids like camphor, naphthalene and iodine ar... Purification: crystallization, sublimation, distillation, differential extraction 1 answer
Match List I with List II.List I (Conversion): A. 1 mol of H_2O to O_2 B. 1 mol of MnO_4^- to Mn^2+ C. 1.5 mol of Ca from molten CaCl_2 D. 1 mol of FeO to Fe_2O_3List II (Number of Faraday required): I. 3F II. 2F III. 1F IV. 5FChoose the correct answ… Answer: 2. A-II, B-IV, C-I, D-III Key idea: Faradays = moles of electrons transferred. A: 2H₂O→ O₂+4H^++4e^- , so 1 mol H₂O needs 2 F (II).... Electrolytic and galvanic cells, electrode potentials 1 answer
Which reaction is NOT a redox reaction? Answer: 1. BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl Key idea: a redox reaction has a change in oxidation numbers. BaCl₂+Na₂SO₄→ BaSO₄+2NaCl is a doubl... Oxidation and reduction, oxidation number 1 answer
The highest number of helium atoms is in Answer: 2. 4 mol of helium Key idea: convert each to number of atoms (He is monoatomic). 2.271098 L at STP (22.7 L/mol): 0.1 mol. 4 mol: 4 m... Atomic and molecular masses, mole concept, molar mass 1 answer
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 Answer: 3. 250 mg Key idea: find the limiting reagent for NaOH+HCl→ NaCl+H₂O . NaOH: 1/40=0.025 mol = 25 mmol. HCl: 25×0.75=18.75 mmol. Left... Chemical equations and stoichiometry 1 answer
The most stable carbocation among the following is: Answer: 1. [structure: methylcyclohexyl carbocation, see figure] Key idea: carbocation stability: tertiary > secondary > primary, and more h... Bond fission, free radicals, carbocations, carbanions and their stability 1 answer
A compound with a molecular formula of C_6H_14 has two tertiary carbons. Its IUPAC name is: Answer: 4. 2,3-dimethylbutane Key idea: a tertiary carbon is bonded to three other carbons (one C-H). 2,2-dimethylbutane: one quaternary C,... Nomenclature (trivial and IUPAC) 1 answer
Match List I with List II.List I (Quantum Number): A. m_l B. m_s C. l D. nList II (Information provided): I. shape of orbital II. size of orbital III. orientation of orbital IV. orientation of spin of electronChoose the correct answer from the option… Answer: 3. A-III, B-IV, C-I, D-II Key idea: each quantum number gives one property of the electron or orbital. m_l : orientation of the orbi... Quantum numbers and shapes of s, p, d orbitals 1 answer
The reagents with which glucose does not react to give the corresponding tests/products areA. Tollen's reagent B. Schiff's reagent C. HCN D. NH_2OH E. NaHSO_3Choose the correct options from the given below: Answer: 4. B and E Key idea: glucose exists mostly as the cyclic hemiacetal, so it gives some but not all aldehyde reactions. Tollens' reage... Carbohydrates: classification, glucose, fructose 1 answer
Match List I with List II.List I (Molecule): A. ethane B. ethene C. carbon molecule, C_2 D. ethyneList 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-bo… Answer: 4. A-III, B-IV, C-II, D-I Key idea: count the bond between the two carbons. Ethane H₃C-CH₃ : one σ bond (III). Ethene: one σ + one π... Valence bond theory, hybridization (s, p, d), resonance 1 answer
Match List I with List II.List I (Compound): A. NH_3 B. BrF_5 C. XeF_4 D. SF_6List II (Shape/geometry): I. Trigonal Pyramidal II. Square Planar III. Octahedral IV. Square PyramidalChoose the correct answer from the options given below: Answer: 2. A-I, B-IV, C-II, D-III Key idea: use VSEPR to get the shape of each molecule. NH₃ : 3 bond pairs + 1 lone pair gives trigonal pyr... VSEPR theory and shapes of molecules 1 answer
Match List I with List II.List I (Process): A. Isothermal process B. Isochoric process C. Isobaric process D. Adiabatic processList II (Conditions): I. No heat exchange II. Carried out at constant temperature III. Carried out at constant volume IV. C… Answer: 1. A-II, B-III, C-IV, D-I Key idea: the prefix tells the fixed quantity. Isothermal: constant temperature (II). Isochoric: constant... System, surroundings, extensive/intensive properties, state functions, processes 1 answer
Arrange the following elements in increasing order of first ionization enthalpy:Li, Be, B, C, NChoose the correct answer from the options given below: Answer: 3. Li < B < Be < C < N Key idea: ionization enthalpy increases across a period, with exceptions at Be (filled 2s) and N (half-filled... Ionization enthalpy and electron gain enthalpy 1 answer
For the reaction 2A ⇌ B + C, K_c = 4×10^-3. At a given time, the composition of reaction mixture is : [A]=[B]=[C]=2×10^-3 M.Then, which of the following is correct? Answer: 4. Reaction has a tendency to go in backward direction. Key idea: compare the reaction quotient Q_c with K_c . Q_c=[B][C]/[A]²=frac(... Law of chemical equilibrium, Kp and Kc 1 answer
In which of the following equilibria, K_p and K_c are NOT equal? Answer: 2. PCl_(5(g)) ⇌ PCl_(3(g)) + Cl_(2(g)) Key idea: K_p=K_c(RT)^(Δ n_g) . They are equal only when Δ n_g=0 . 2BrCl⇌ Br₂+Cl₂ : Δ n_g=0 .... Law of chemical equilibrium, Kp and Kc 1 answer
Given below are two statements:Statement I : Aniline does not undergo Friedel-Crafts alkylation reaction.Statement II : Aniline cannot be prepared through Gabriel synthesis.In the light of the above statements, choose the correct answer from the opti… Answer: 2. Both Statement I and Statement II are true. Key idea: the -NH₂ group of aniline is basic and reacts with Lewis acids; Gabriel syn... Amines: nomenclature, classification, structure, preparation 1 answer
Identify the correct reagents that would bring about the following transformation.[structure transformation shown in figure: ring-CH_2-CH=CH_2 → ring-CH_2-CH_2-CHO] Answer: 3. (i) BH₃ (ii) H₂O₂/oversetominusOH (iii) PCC Key idea: the -CH=CH₂ group must become -CH₂CH₂CHO , a terminal aldehyde, which needs... Aldehydes and ketones: HCN, NH3 derivatives, Grignard, oxidation, reduction (Wolff-Kishner, Clemmensen) 1 answer
Among Group 16 elements, which one does NOT show -2 oxidation state? Answer: 1. Po Key idea: metallic character increases down the group, so the -2 state becomes unfavourable. O, S, Se and Te form oxides, sulp... General trends, Group 15 and 16 1 answer
Two heaters A and B have power rating of 1 kW and 2 kW, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is: Answer: 3. 2 : 9 Key idea: P=V²/R , so R∝1/P at fixed voltage. Take R_A=2 units (1 kW) and R_B=1 unit (2 kW). Series: R_s=3 , so P_s=V²/3 .... Electrical energy and power 1 answer
Choose the correct circuit which can achieve the bridge balance. Answer: 2. circuit (2) Key idea: A Wheatstone bridge is balanced when no current flows through G, i.e. P/Q=R/S . The top arms are 10 Ω and 1... Wheatstone bridge and metre bridge 1 answer
A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to :A. hold the sheet there if it is magnetic.B. hold the sheet there if it is non-magnetic.C. move the sheet away from the pole with uniform velocity if… Answer: 3. A and C only Key idea: A force is needed only if the magnetic pole exerts a force on the sheet. A: A magnetic sheet is attracted... Lenz's law and eddy currents 1 answer
A 10 μ F capacitor is connected to a 210 V, 50 Hz source as shown in figure. The peak current in the circuit is nearly (π=3.14): Answer: 3. 0.93 A Key idea: For a capacitor in an AC circuit the capacitive reactance is X_C=1/ω C and the peak current is I₀=V₀/X_C=V₀ω C ,... Reactance, impedance, LCR series circuit, resonance 1 answer
A parallel plate capacitor is charged by connecting it to a battery through a resistor. If I is the current in the circuit, then in the gap between the plates : Answer: 3. displacement current of magnitude equal to I flows in the same direction as I. Key idea: Maxwell's displacement current I_d=ε₀dΦ_... Displacement current 1 answer
The property which is not of an electromagnetic wave travelling in free space is that : Answer: 1. they originate from charges moving with uniform speed. Key idea: Electromagnetic waves are produced by accelerated (oscillating)... EM waves, characteristics and transverse nature 1 answer

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