Sulphur exhibit variable Valency due to
Presence of d orbital in sulphur correct as per chemistry principle.
Ref: NCERT Chemistry Class XII — Electrochemistry
#oxidation states
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Which of the following lanthanoids exhibits the +2 oxidation state due to a half-filled 4f subshell?
Given: Which of the following lanthanoids exhibits the +2 oxidation state due to a half-filled 4f subshell? These values define the system as per NCERT data. Formula: Eu (Z = 63) forms Eu^{2+ with 4fâ·, a stable half-filled configuration.. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substituting values like 1.2 × 10â»âµ, 236 J kgâ»Â¹ Kâ»Â¹, 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»Â¹ Kâ»Â¹
Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.
Which of the following lanthanoids exhibits a +4 oxidation state due to its noble gas configuration?
Given: Which of the following lanthanoids exhibits a +4 oxidation state due to its noble gas configuration? These values define the system as per NCERT data. Formula: Cerium (Ce, Z = 58) forms Ce^{4+ with 4fâ° (noble gas-like), making it stable in this state.. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substituting values like 1.2 × 10â»âµ, 236 J kgâ»Â¹ Kâ»Â¹, 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
Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Relevant Chemistry topic covering principles and examples as per NCERT.
Which lanthanoid commonly exhibits both +2 and +3 oxidation states due to extra stability of half-filled f-orbitals?
Europium (Eu) shows +2 oxidation state due to the stability of half-filled 4f 7 configuration, along with the common +3 state.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Oxidation States and Colour and Magnetic Properties of d-Block
Which transition metal exhibits the +1 oxidation state most frequently?
Cu + is common due to the stability of the 3d 10 configuration.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Lanthanoids - Electronic Configuration and Lanthanoid Contraction
Which of the following lanthanoids shows +4 oxidation state?
Cerium (Ce) exhibits +4 oxidation state due to the stability of empty 4f orbitals (4f 0 ).
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Lanthanoids - Electronic Configuration and Lanthanoid Contraction
Which of the following is a consequence of lanthanoid contraction?
Lanthanoid contraction causes similar atomic radii of Zr (160 pm) and Hf (159 pm), making their separation difficult.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Lanthanoids - Electronic Configuration and Lanthanoid Contraction
What is the primary reason for the variable oxidation states in transition elements?
Comparable energies of (n-1)d and ns orbitals allow for variable electron loss.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: General Properties of d-Block - Electronic Configuration and Trends
Which of the following is NOT a characteristic of transition metal complexes?
Transition metal complexes are typically colored due to d-d transitions.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Actinoids and Comparison of Lanthanoids and Actinoids
Which of the following statements about actinoids is INCORRECT?
Actinoids are all radioactive, contrary to the incorrect option.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Actinoids and Comparison of Lanthanoids and Actinoids
Which compound contains an element with an oxidation number lower than in CO₂?
C in CO₂: +4. In CH₂O: x + 2(+1) + (-2) = 0, x = 0, which is lower.
Ref: NCERT Class 11 Chemistry > Chapter 7: Redox Reactions > Topic: Electrode Potential and Electrochemical Series and Galvanic Cells
Which group 16 element has the highest tendency to form stable compounds in the +4 oxidation state?
The +4 oxidation state is most stable for S in group 16, forming SO₂ (gaseous, strong S=O bonds), more stable than O₂, SeO₂ (polymeric), or TeO₂ (solid).
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
