CHEMISTRY

CHEMISTRY

What is the mass percentage of potassium in KMnOâ‚„? (Atomic masses: K = 39, Mn = 55, O = 16)

Given: What is the mass percentage of potassium in KMnO₄? (Atomic masses: K = 39, Mn = 55, O = 16) These values define the system as per NCERT data. Formula: Molar mass = 39 + 55 + (4 × 16) = 39 + 55 + 64 = 158 g/mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of K = 39 g. % K = (39 / 158) × 100 ≈ 24.68%. 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

Which product is formed when benzoic acid is treated with PClâ‚…?

Benzoic acid reacts with phosphorus pentachloride (PClâ‚…) to form benzoyl chloride. 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 number of unpaired electrons in [Cr(Hâ‚‚O)6]^{3+ ?

Given: What is the number of unpaired electrons in [Cr(H₂O)6]^{3+ ? These values define the system as per NCERT data. Formula: Cr³⁺ ( d³ ) with H₂O in an octahedral field has 3 unpaired electrons ( t_{2g³ ), as it’s a d³ system.. 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: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

Which principle states that no two electrons in an atom can have the same set of four quantum numbers?

The Pauli exclusion principle restricts two electrons from having identical quantum numbers, ensuring opposite spins in the same orbital. 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

Which of the following acids is the most acidic?

Trichloroacetic acid is the most acidic due to the strong electron-withdrawing effect of chlorine atoms. 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

Which of the following compounds exhibits the highest boiling point?

Among alcohols, phenols, and ethers, alcohols have the highest boiling points due to hydrogen bonding. 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 mass percentage of oxygen in K₂Cr₂O₇? (Atomic masses: K = 39, Cr = 52, O = 16)

Given: What is the mass percentage of oxygen in K₂Cr₂O₇? (Atomic masses: K = 39, Cr = 52, O = 16) These values define the system as per NCERT data. Formula: Molar mass = (2 × 39) + (2 × 52) + (7 × 16) = 78 + 104 + 112 = 294 g/mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of O = 112 g. % O = (112 / 294) × 100 ≈ 38.1%. 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

Which of the following elements forms a compound with hydrogen of the type XH_3?

Given: Which of the following elements forms a compound with hydrogen of the type XH_3? These values define the system as per NCERT data. Formula: Group 15 elements (ns²np³) like nitrogen form NH_3, using 3 valence electrons to bond with H.. 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: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

The first element of Group 13 shows anomalous behavior due to:

Boron (Group 13) has a small size, high electronegativity, and only 2s/2p orbitals, limiting its covalency to 4, unlike Al. 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 heat released when 15.4 g of butane (C₄H₁₀) burns completely? (Δ H° = -2877.3 kJ/mol, molar mass = 5

Given: What is the heat released when 15.4 g of butane (C₄H₁₀) burns completely? (Δ H° = -2877.3 kJ/mol, molar mass = 58 g/mol) These values define the system as per NCERT data. Formula: Moles = 15.4 / 58 = 0.2655 mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Heat = 0.2655 × 2877.3 = 763.9 kJ. 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

Which molecule has a single covalent bond formed by sharing two electrons between a hydrogen and a halogen atom?

In HBr, hydrogen and bromine share one pair of electrons (2 electrons), forming a single covalent bond. 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

Which of the following compounds will react most readily with Lucas reagent?

Lucas test differentiates primary, secondary, and tertiary alcohols based on their reactivity with ZnCl â‚‚ and HCl. Tertiary alcohols react fastest. 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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