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CHEMISTRY

This chemistry category brings together practice questions from across the subject, including physical, organic and inorganic chemistry. Use it to revise reactions and concepts, practise calculation-based problems, and find out which topics need a second pass.

45 questions

CHEMISTRY

What is the degree of dissociation of 0.025 M methanoic acid if its molar conductivity is 46.1 S cm² mol⁻¹, given la

Given: What is the degree of dissociation of 0.025 M methanoic acid if its molar conductivity is 46.1 S cm² mol⁻¹, given lambda⁰(H^+) = 349.6 S cm² mol^{-1 and lambda⁰(HCOO^-) = 54.6 S cm² mol^{-1 ? These values define the system as per NCERT data. Formula: Lambda_m⁰ = 349.6 + 54.6 = 404.2 S cm² mol^{-1. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: α = Lambda_m/Lambda_m⁰ = 46.1/404.2 approx 0.114 . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.

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CHEMISTRY

In combustion analysis, 0.36 g of a compound gave 0.36 g of Hâ‚‚O . What is the percentage of hydrogen? (Atomic masses:

Given: In combustion analysis, 0.36 g of a compound gave 0.36 g of H₂O . What is the percentage of hydrogen? (Atomic masses: H = 1, O = 16) These values define the system as per NCERT data. Formula: Molar mass of H₂O = 18 g/mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of H = 2 × 0.36/18 = 0.04 g. Percentage = 0.04 × 100/0.36 = 11.11% . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.

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CHEMISTRY

In the Dumas method, 0.5 g of a compound gave 112 mL of Nâ‚‚ at STP. What is the percentage of nitrogen? (Atomic mass: N

Given: In the Dumas method, 0.5 g of a compound gave 112 mL of N₂ at STP. What is the percentage of nitrogen? (Atomic mass: N = 14) These values define the system as per NCERT data. Formula: Mass of N₂ = 28 × 112/22400 = 0.14 g. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of N = 0.14 g. Percentage = 0.14 × 100/0.5 = 28% . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.

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CHEMISTRY

What is the mass percentage of sulfur in Na₂S₂O₃? (Atomic masses: Na = 23, S = 32, O = 16)

Given: What is the mass percentage of sulfur in Na₂S₂O₃? (Atomic masses: Na = 23, S = 32, O = 16) These values define the system as per NCERT data. Formula: Molar mass = (2 × 23) + (2 × 32) + (3 × 16) = 46 + 64 + 48 = 158 g/mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of S = 2 × 32 = 64 g. % S = (64 / 158) × 100 ≈ 40.51%. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.

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CHEMISTRY

What is the oxidation number of Cl in ClO₃^- ?

O is -2, total charge is -1. Let Cl be x : x + 3(-2) = -1, x - 6 = -1, x = +5 . This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.

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CHEMISTRY

What is the pH of a 0.001 M Ba(OH)2 solution, assuming complete dissociation?

Given: What is the pH of a 0.001 M Ba(OH)2 solution, assuming complete dissociation? These values define the system as per NCERT data. Formula: [OH-] = 2 × 0.001 = 0.002 M, pOH = -log(0.002) approx 2.7. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: pH = 14 - 2.7 = 11.3 . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Solutions, Topic: Concentration terms and colligative properties.

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CHEMISTRY

What is the product when (CH₃)2NH reacts with HNO₂ ?

Given: What is the product when (CH₃)2NH reacts with HNO₂ ? These values define the system as per NCERT data. Formula: Secondary amines like (CH₃)2NH react with HNO₂ to form yellow oily N-nitrosoamines, (CH₃)2N-N=O, without gas evolution.. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substituting values like 1.2 × 10⁻⁵, 236 J kg⁻¹ K⁻¹, CH₃CH₂NH₂ etc. into the formula and simplifying step by step. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.

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CHEMISTRY

Which of the following amines reacts with CH₃COCl to form an amide?

Primary amines like CH₃CH₂NH₂ react with acetyl chloride ( CH₃COCl ) to form amides ( CH₃CONHCH₂CH₃ ), while tertiary amines do not. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.

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CHEMISTRY

Which complex shows ionization isomerism with [Co(NH₃)5SO₄]Br ?

Ionization isomerism involves different ions outside the coordination sphere. [Co(NH₃)5Br]SO₄ is an ionization isomer of [Co(NH₃)5SO₄]Br, as Br^- and SO₄^{2- switch positions.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Organic Chemistry - Basic Principles, Hydrocarbons and Reaction Mechanisms, Topic: Nomenclature, isomerism and reaction types.

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CHEMISTRY

What is the molality of a solution containing 8 g of NaOH in 400 g of water? (Molar mass of NaOH = 40 g/mol)

Given: What is the molality of a solution containing 8 g of NaOH in 400 g of water? (Molar mass of NaOH = 40 g/mol) These values define the system as per NCERT data. Formula: Moles = 8 / 40 = 0.2 mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of solvent = 0.4 kg. Molality = 0.2 / 0.4 = 0.5 m. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

The Henry's law constant for a gas in water is 4 × __10POW₄__bar at 298 K. What is the mole fraction of the gas under

Given: The Henry's law constant for a gas in water is 4 × __10POW₄__bar at 298 K. What is the mole fraction of the gas under a partial pressure of 2 bar? These values define the system as per NCERT data. Formula: p = K_H · x. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: 2 = 4 × __10POW₄__ · x . x = 2/4 × __10POW₄__= 5 × 10⁻⁵. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

What is the electronic configuration of chromium (Z = 24), considering its exceptional stability?

Given: What is the electronic configuration of chromium (Z = 24), considering its exceptional stability? These values define the system as per NCERT data. Formula: Chromium’s configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹ instead of 3d⁴ 4s² due to the extra stability of a half-filled 3d subshell.. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substituting values like 1.2 × 10⁻⁵, 236 J kg⁻¹ K⁻¹, CH₃CH₂NH₂ etc. into the formula and simplifying step by step. Result: The computed value matches the expected outcome

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.

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