CHEMISTRY

CHEMISTRY

In the Carius method, 0.25 g of a compound gave 0.574 g of AgBr . What is the percentage of bromine? (Atomic masses: Ag

Given: In the Carius method, 0.25 g of a compound gave 0.574 g of AgBr . What is the percentage of bromine? (Atomic masses: Ag = 108, Br = 80) These values define the system as per NCERT data. Formula: Molar mass of AgBr = 108 + 80 = 188 g/mol. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Mass of Br = 80 × 0.574/188 = 0.244 g. Percentage = 0.244 × 100/0.25 = 97.6% . 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 NCER

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

A reaction’s rate increases by a factor of 16 when [A] is doubled and [B] is doubled. If the order with respect to A i

Given: A reaction’s rate increases by a factor of 16 when [A] is doubled and [B] is doubled. If the order with respect to A is 2, what is the order with respect to B? These values define the system as per NCERT data. Formula: Rate = k[A]^n[B]^m, n = 2, 16 = 2² × 2^m. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: 16 = 4 × 2^m, 2^m = 4, m = 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: Relevant Chemistry topic covering principles and examples as per NCERT.

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CHEMISTRY

What is the number of unpaired electrons in [Mn(Hâ‚‚O)6]^{2+ ?

Given: What is the number of unpaired electrons in [Mn(Hâ‚‚O)6]^{2+ ? These values define the system as per NCERT data. Formula: Mn²⁺ ( d⁵ ) with weak field Hâ‚‚O in an octahedral field is high spin ( t_{2g³ e_g² ), with 5 unpaired electrons.. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substituting values like 1.2 × 10⁻⁵, 236 J kg⁻¹ K⁻¹, CH₃CHâ‚‚NHâ‚‚ 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 kgâ

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 valence electrons are contributed by nitrogen in the NH₃ molecule?

Nitrogen has 5 valence electrons ( 2s² 2p³ ), which it contributes to NH₃ for bonding and lone pairs. 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 atomic number of an element with 3 electrons in its 2p subshell?

Given: What is the atomic number of an element with 3 electrons in its 2p subshell? These values define the system as per NCERT data. Formula: Total electrons = 2 + 2 + 3 = 7, so Z = 7 (nitrogen).. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Configuration up to 2p with 3 electrons: 1s² 2s² 2p³. 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 total number of sigma ( sigma ) bonds in CH₃CH₂OCH₃ ?

In CH₃CH₂OCH₃, there are 9 single bonds: 8 C-H, 1 C-C, and 2 C-O. Each single bond is a sigma bond, totaling 9. 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 0.003 M NaOH solution, assuming complete dissociation?

Given: What is the pH of a 0.003 M NaOH solution, assuming complete dissociation? These values define the system as per NCERT data. Formula: [OH-] = 0.003 M, pOH = -log(0.003) approx 2.52. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: pH = 14 - 2.52 = 11.48 approx 11.5 . 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: Solutions, Topic: Concentration terms and colligative properties.

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CHEMISTRY

What is the product when (CH₃)2CHNH₂ reacts with excess CH₃I followed by AgOH ?

Propan-2-amine with excess CH₃I forms a quaternary salt ( (CH₃)2CHN(CH₃)3+I- ), which with AgOH undergoes elimination to yield (CH₃)2CHN(CH₃)2 .

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 produces 2 moles of AgCl per mole when treated with excess AgNO₃ ?

[Co(NH₃)5Cl]Cl₂ has 2 ionizable Cl^- ions outside the coordination sphere, yielding 2 moles of AgCl, while the inner Cl is non-ionizable. 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 complex is diamagnetic?

[Ni(CN)4]^{2- has Ni²⁺ ( d⁸ ), and with strong field CN^- ligands in a square planar geometry ( dsp² ), all electrons pair up, resulting in 0 unpaired electrons, making it diamagnetic.

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 reaction 2Na + 2Hâ‚‚O -> 2NaOH + Hâ‚‚, what is the oxidation state change for Na?

Na goes from 0 in elemental form to +1 in NaOH, an increase of +1, indicating oxidation. 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 of nickel deposited at the cathode when a 5 A current flows through Ni(NO₃)₂ solution for 20 minute

Given: What is the mass of nickel deposited at the cathode when a 5 A current flows through Ni(NO₃)₂ solution for 20 minutes? (Molar mass of Ni = 58.7 g/mol, F = 96500 C/mol) These values define the system as per NCERT data. Formula: Q = 5 × 1200 = 6000 C. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: For Ni²⁺ + 2e⁻ → Ni(s), 2F (193000 C) deposits 58.7 g. Mass = 58.7 × 6000/193000 approx 1.824 g . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s

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

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