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#electron configuration

49 public questions tagged with this topic.

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

How many electrons are in the L shell of an atom with 10 electrons?

Given: How many electrons are in the L shell of an atom with 10 electrons? These values define the system as per NCERT data. Formula: The L shell (n = 2) has 2s² 2p⁶ = 2 + 6 = 8 electrons.. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: For 10 electrons (neon): 1s² 2s² 2p⁶. 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 complex has the highest number of unpaired electrons?

[Fe(H₂O)6]^{3+ (Fe³⁺, d⁵ ) with weak field H₂O is high spin ( t_{2g³ e_g² ), with 5 unpaired electrons, the highest among the options. 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 subshell has the lowest energy for n = 4 in a multi-electron atom?

Given: Which subshell has the lowest energy for n = 4 in a multi-electron atom? These values define the system as per NCERT data. Formula: For n = 4, 4s (l = 0) has the lowest energy, followed by 4p, 4d, 4f.. This is standard NCERT relation. Substitution & Calculation: In multi-electron atoms, energy increases with l for a given n. Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: d and f Block Elements, Topic: Lanthanoid contraction due to poor shielding of 4f orbitals.

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CHEMISTRY

The number of electrons in the valence shell of an element with configuration 1s² 2s² 2p⁶ 3s² is:

Given: The number of electrons in the valence shell of an element with configuration 1s² 2s² 2p⁶ 3s² is: Formula: Magnesium (Mg, Z=12) has 3s² in its valence shell (n=3), totaling 2 valence electrons.. 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 of the following ions has a 3d⁸ configuration?

Given: Which of the following ions has a 3d⁸ configuration? These values define the system as per NCERT data. Formula: Ni (Z = 28): 3d⁸ 4s². This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Ni^{2+ : 3d⁸ (loses 2 from 4s). 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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