CHEMISTRY

CHEMISTRY

What is the mole fraction of NaCl in a solution containing 5.85 g of NaCl and 90 g of water? (Molar masses: NaCl = 58.5

Given: What is the mole fraction of NaCl in a solution containing 5.85 g of NaCl and 90 g of water? (Molar masses: NaCl = 58.5 g/mol, H₂O = 18 g/mol) These values define the system as per NCERT data. Formula: Moles of NaCl = 5.85 / 58.5 = 0.1 mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Moles of H₂O = 90 / 18 = 5 mol. Total moles = 0.1 + 5 = 5.1. Mole fraction = 0.1 / 5.1 ≈ 0.0196. 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

A gaseous reaction follows Rate = k p_A² with k = 0.2 atm^{-1 s^{-1 and p_A = 0.5 atm . What is the rate in atm s^{-1 ?

Given: A gaseous reaction follows Rate = k p_A² with k = 0.2 atm^{-1 s^{-1 and p_A = 0.5 atm . What is the rate in atm s^{-1 ? These values define the system as per NCERT data. Formula: Rate = k p_A² = 0.2 × (0.5)² = 0.2 × 0.25 = 0.05 .. 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⁻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

How many pi bonds are present in the Câ‚‚Hâ‚‚ molecule?

Câ‚‚Hâ‚‚ has a triple bond between carbons (1 sigma, 2 pi), totaling 2 pi bonds. 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: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

The boiling point elevation of a 0.15 m aqueous KCl solution is 0.156 K. What is the van't Hoff factor? ( K_b = 0.52 K k

Given: The boiling point elevation of a 0.15 m aqueous KCl solution is 0.156 K. What is the van't Hoff factor? ( K_b = 0.52 K kg/mol ) These values define the system as per NCERT data. Formula: Δ T_b = i · K_b · m. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: 0.156 = i × 0.52 × 0.15 . i = 0.156/0.52 × 0.15 = 0.156/0.078 = 2 . 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

The number of unpaired electrons in Ti^{3+ (Z = 22) is:

Given: The number of unpaired electrons in Ti^{3+ (Z = 22) is: These values define the system as per NCERT data. Formula: Ti: 3d² 4s². This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Ti^{3+ : 3d¹ (loses 2 from 4s, 1 from 3d). 1 unpaired electron. 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

How many electrons are transferred in the reduction of 1 mol of Oâ‚‚ to Hâ‚‚O in acidic medium?

Reaction: Oâ‚‚ + 4H+ + 4e- -> 2Hâ‚‚O . 4 electrons per mole of Oâ‚‚. 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: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

What is the primary valence of nickel in NiCl₂ · 6H₂O ?

In NiCl₂ · 6H₂O, formulated as [Ni(H₂O)6]Cl₂, the primary valence is the oxidation state of Ni, satisfied by 2 ionizable Cl^- ions, so it is 2. 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

The number of moles of Fe^{2+ oxidized by 1 mole of K₂Cr₂O₇ in acidic medium is:

Cr₂O₇^{2- + 14H^+ + 6Fe^{2+ -> 2Cr^{3+ + 6Fe^{3+ + 7H₂O . 1 mole K₂Cr₂O₇ oxidizes 6 moles Fe^{2+ . 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: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

What is the pH of a solution with [OH-] = 2.5 × 10⁻² M?

Given: What is the pH of a solution with [OH-] = 2.5 × 10⁻² M? These values define the system as per NCERT data. Formula: pOH = -log(2.5 × 10⁻²) approx 1.6, pH = 14 - 1.6 = 12.4 .. 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⁻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

Which complex is used in the purification of nickel?

[Ni(CO)4] is volatile and used in the Mond process to purify nickel, unlike the others. 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: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

What is the ll potential of a hydrogen electrode in a solution with pH = 4 at 298 K, given E⁰ = 0 V ?

Given: What is the ll potential of a hydrogen electrode in a solution with pH = 4 at 298 K, given E⁰ = 0 V ? These values define the system as per NCERT data. Formula: For H+ + e- -> 1/2 H₂, E = E⁰ - 0.059/1 log frac1[H^+]. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: [H^+] = 10⁻⁴, E = 0 - 0.059 × 4 = -0.236 V . 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

The Henry's law constant for a gas in water is 8 × __10POW₃__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 8 × __10POW₃__bar at 298 K. What is the mole fraction of the gas under a partial pressure of 0.4 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: 0.4 = 8 × __10POW₃__ · x . x = 0.4/8 × __10POW₃__= 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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