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#chemical reactions

27 public questions tagged with this topic.

CHEMISTRY

What is Δ H for C₆H₆(l) + 15/2O₂(g) -> 6CO₂(g) + 3H₂O(l) if Δ_f H°: C₆H₆(l) = 49 kJ/mol, CO₂(g) = -393.5 kJ/mol, H₂O(l)

Given: What is Δ H for C₆H₆(l) + 15/2O₂(g) -> 6CO₂(g) + 3H₂O(l) if Δ_f H°: C₆H₆(l) = 49 kJ/mol, CO₂(g) = -393.5 kJ/mol, H₂O(l) = -285.8 kJ/mol? Formula: Δ_r H = [6(-393.5) + 3(-285.8)] - [49 + 0] = -2361 - 857.4 - 49 = -3267.4 kJ/mol.. 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

Which compound does not undergo Friedel-Crafts acylation?

Pyridine does not undergo Friedel-Crafts acylation due to the presence of a lone pair on nitrogen, which deactivates the ring. This follows from NCERT principle where relation explains outcome clearly for students.

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

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Preparation and Properties of Potassium Dichromate and Permanganate

Which of the following reactions represents the preparation of K 2 Cr 2 O 7 from chromite ore?

Chromite ore is oxidized with Na 2 CO 3 in the presence of air to form sodium chromate: 4FeCr 2 O 4 + 8Na 2 CO 3 + 7O 2 → 8Na 2 CrO 4 + 2Fe 2 O 3 + 8CO 2 . This is the key step in the preparation of K 2 Cr 2 O 7 .

Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Preparation and Properties of Potassium Dichromate and Permanganate

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Fundamental Concepts - Reaction Mechanism - Fission and Reaction Intermediates

Which species is least likely to act as an electrophile in a reaction with CH₃CH=CH₂?

CH₃⁻ is electron-rich (carbanion), making it a nucleophile, not an electrophile, unlike the others which are electron-deficient.

Ref: NCERT Class 11 Chemistry > Chapter 8: Organic Chemistry - Some Basic Principles and Techniques > Topic: Fundamental Concepts - Reaction Mechanism - Fission and Reaction Intermediates

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