CHEMISTRY

CHEMISTRY

Which of the following amines has the nitrogen atom with the greatest lone pair availability for protonation?

In (CH₃)2NH, the lone pair is enhanced by the inductive effect of two methyl groups and not delocalized (unlike aniline), making it highly available for protonation.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII), Chapter: Chemical Bonding (Latest NCERT 2026-27), Topic: Hybridization of nitrogen in CH₃NH₂, sp³ hybridization and pyramidal geometry

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CHEMISTRY

Which complex shows geometrical isomerism?

[Co(NH₃)4Cl₂]+ is octahedral and can form cis and trans isomers due to two Cl^- ligands. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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CHEMISTRY

Which complex has an octahedral coordination polyhedron?

[Fe(CN)6]^{3- has 6 CN^- ligands around Fe³⁺, forming an octahedral geometry, unlike the tetrahedral or square planar options. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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CHEMISTRY

What is the approximate ratio of the radius of an atom to its nucleus?

Rutherford’s model states the atomic radius is about 10⁻¹⁰m and the nuclear radius is 10⁻¹⁵m, giving a ratio of 10⁻¹⁰/ 10⁻¹⁵= __10POW₅__. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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CHEMISTRY

What is the formal charge on the carbon atom in the CO₃²- ion in one of its resonance structures?

In one resonance structure of CO₃²-, carbon has 1 double bond (4 electrons) and 2 single bonds (4 electrons). Formal charge = 4 - 0 - 1/2 × 8 = 0. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII), Chapter: Electrochemistry (Latest NCERT 2026-27), Topic: Faraday's laws, charge required to reduce Al³⁺, 3F = 3 × 96500 C

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CHEMISTRY

Calculate the boiling point elevation of a solution containing 7.2 g of glucose ( C₆H₁₂O₆ ) in 300 g of water. ( K_b = 0

Given: Calculate the boiling point elevation of a solution containing 7.2 g of glucose ( C₆H₁₂O₆ ) in 300 g of water. ( K_b = 0.52 K kg/mol, Molar mass of glucose = 180 g/mol ) Formula: Moles of glucose = 7.2/180 = 0.04 mol. Substitution & Calculation: Molality = 0.04/0.3 = 0.133 mol/kg . Δ T_b = 0.52 × 0.133 = 0.069 K . Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII), Chapter: Solutions (Latest NCERT 2026-27), Topic: Colligative properties, ΔT_b = K_b·m, urea NH₂CONH₂ example

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CHEMISTRY

The initial rate of a reaction is 1.8 × 10⁻³mol L^{-1 s^{-1 when [A] = 0.2 M and [B] = 0.3 M. If the rate law is Rate =

Given: The initial rate of a reaction is 1.8 × 10⁻³mol L^{-1 s^{-1 when [A] = 0.2 M and [B] = 0.3 M. If the rate law is Rate = k[A]²[B], what is k in L² mol^{-2 s^{-1 ? Formula: k = fracRate[A]²[B] = frac1.8 × 10⁻³(0.2)² × 0.3 = frac1.8 × 10⁻³⁰.012 = 0.15 .. Substitution: Substituting given values into formula as per NCERT 2026-27 method. Calculation: Simplifying step by step with proper SI units like m/s², J kg⁻¹ K⁻¹, 10⁻⁵, A m⁻¹ etc. Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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CHEMISTRY

What is the potential of a hydrogen electrode in a solution with pH = 5 at 298 K, given E⁰ = 0 V ?

Given: What is the potential of a hydrogen electrode in a solution with pH = 5 at 298 K, given E⁰ = 0 V ? Formula: For H+ + e- -> 1/2 H₂, E = E⁰ - 0.059/1 log frac1[H^+]. Substitution & Calculation: [H^+] = 10⁻⁵, E = 0 - 0.059 × 5 = -0.295 V . Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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CHEMISTRY

How many optical isomers are possible for [PtCl₂(en)2]^{2+ ?

The cis isomer of [PtCl₂(en)2]^{2+ (square planar) is chiral due to two bidentate en ligands, forming 2 optical isomers (d and l). This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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CHEMISTRY

2 moles of an ideal gas expand isothermally from 6 L to 18 L against a constant pressure of 1 atm at 340 K. Calculate th

Given: 2 moles of an ideal gas expand isothermally from 6 L to 18 L against a constant pressure of 1 atm at 340 K. Calculate the work done (1 L · atm = 101.3 J). Formula: w = -p_{ex Δ V. Substitution & Calculation: Δ V = 18 - 6 = 12 L, p_{ex = 1 atm. w = -1 × 12 = -12 L · atm = -12 × 101.3 = -1215.6 J = -1.22 kJ. Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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CHEMISTRY

For the reaction 3A -> 2B + C, the concentration of A decreases from 0.27 M to 0.24 M in 15 seconds. What is the average

Given: For the reaction 3A -> 2B + C, the concentration of A decreases from 0.27 M to 0.24 M in 15 seconds. What is the average rate of formation of B in mol L^{-1 s^{-1 ? Formula: Rate = -1/3 fracΔ[A]Δ t = 1/2 fracΔ[B]Δ t = fracΔ[C]Δ t. Substitution & Calculation: Δ[A] = 0.24 - 0.27 = -0.03 mol L^{-1, Δ t = 15 s . -fracΔ[A]Δ t = 2.0 × 10⁻³, so fracΔ[B]Δ t = 2/3 × 2.0 × 10⁻³= 1.33 × 10⁻³. Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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CHEMISTRY

For the reaction 2P + Q -> 3R, the rate of disappearance of Q is 1.5 × 10⁻³mol L^{-1 s^{-1 . What is the rate of formati

Given: For the reaction 2P + Q -> 3R, the rate of disappearance of Q is 1.5 × 10⁻³mol L^{-1 s^{-1 . What is the rate of formation of R? Formula: Rate = -1/2 fracΔ[P]Δ t = -fracΔ[Q]Δ t = 1/3 fracΔ[R]Δ t. Substitution & Calculation: -fracΔ[Q]Δ t = 1.5 × 10⁻³, so fracΔ[R]Δ t = 3 × 1.5 × 10⁻³= 4.5 × 10⁻³. Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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