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CHEMISTRY

Latest questions in this category.

45 questions

CHEMISTRY

A first-order reaction has a rate constant of 0.01155 min^{-1 . What percentage of the reactant remains after 90 minutes

Given: A first-order reaction has a rate constant of 0.01155 min^{-1 . What percentage of the reactant remains after 90 minutes? These values define the system as per NCERT data. Formula: ln frac[R]_0[R] = k t = 0.01155 × 90 = 1.0395. This is standard NCERT relation. Substitution & Calculation: frac[R][R]_0 = e^{-1.0395 = 0.3536 approx 35% . Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

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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CHEMISTRY

Which of the following is an allylic halide?

Allylic halides have a halogen atom attached to an sp3 carbon adjacent to a carbon-carbon double bond. This follows from NCERT principle where relation explains outcome clearly for students.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Haloalkanes and Haloarenes, Topic: Allylic halides, CH₂=CHCH₂Cl as allylic halide.

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CHEMISTRY

The solubility product of MnS is 2.5 × 10⁻¹³. What is its solubility in water?

Given: The solubility product of MnS is 2.5 × 10⁻¹³. What is its solubility in water? These values define the system as per NCERT data. Formula: MnS(s) Mn²+ + S²-, K_{sp = S². This is standard NCERT relation. Substitution & Calculation: S² = 2.5 × 10⁻¹³, S = sqrt2.5 × 10⁻¹³approx 5.0 × 10⁻⁷M. Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

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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CHEMISTRY

Which complex is used in electroplating with gold?

[Au(CN)2]^{- is used in gold electroplating for smooth deposition, unlike the others. 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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CHEMISTRY

Which of the following compounds is formed when CH₃CH₂NH₂ reacts with (CH₃)2CHCHO followed by H₂/Ni ?

Ethanamine reacts with 2-methylpropanal ( (CH₃)2CHCHO ) to form an imine, reduced by H₂/Ni to CH₃CH₂NHCH₂CH(CH₃)2 (N-(2-methylpropyl)ethanamine). This follows from NCERT principle where relation explains outcome clearly for students.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Chemical Bonding and Molecular Structure, Topic: Covalent bonds in CH₃CH₂NH₂, counting bonds, Lewis structure.

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CHEMISTRY

For an endothermic reaction with Δ H > 0 and Δ S < 0, under what condition is it spontaneous?

Given: For an endothermic reaction with Δ H > 0 and Δ S < 0, under what condition is it spontaneous? These values define the system as per NCERT data. Formula: For Δ H > 0 and Δ S < 0, Δ G = Δ H - TΔ S > 0 always, so it is never spontaneous.. This is standard NCERT relation. Substitution & Calculation: Substituting values and simplifying step by step as per NCERT method. Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

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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CHEMISTRY

How many grams of a non-volatile solute (molar mass 180 g/mol) must be dissolved in 540 g of water to reduce its vapor p

Given: How many grams of a non-volatile solute (molar mass 180 g/mol) must be dissolved in 540 g of water to reduce its vapor pressure to 98% of its original value? These values define the system as per NCERT data. Formula: Relative lowering = p⁰ - p/p⁰ = 1 - 0.98 = 0.02. This is standard NCERT relation. Substitution & Calculation: Moles of water = 540/18 = 30 mol . 0.02 = n_2/30, n_2 = 0.6 mol . Mass = 0.6 × 180 = 108 g . Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

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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CHEMISTRY

Which alcohol is commonly used in antifreeze solutions?

Ethylene glycol is widely used as an antifreeze in cooling systems due to its low freezing point. 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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CHEMISTRY

The heat capacity of a calorimeter is 10 kJ/K. If the temperature rises from 298 K to 300 K during a reaction, what is t

Given: The heat capacity of a calorimeter is 10 kJ/K. If the temperature rises from 298 K to 300 K during a reaction, what is the heat absorbed by the calorimeter? These values define the system as per NCERT data. Formula: q = C Δ T. This is standard NCERT relation. Substitution & Calculation: C = 10 kJ/K, Δ T = 300 - 298 = 2 K. So, q = 10 × 2 = 20 kJ. Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

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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CHEMISTRY

Which amine is produced when CH₃CH₂CH₂CH₂NO₂ is reduced with Sn/HCl ?

Reduction of 1-nitrobutane ( CH₃CH₂CH₂CH₂NO₂ ) with Sn/HCl yields CH₃CH₂CH₂CH₂NH₂ (butan-1-amine), a primary amine, followed by neutralization. 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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