7 public questions tagged with this topic.
Actinoids exhibit variable oxidation states due to comparable energies of 5f, 6d, and 7s orbitals, allowing participation of multiple electrons in bonding.
Ref: NCERT Class 12 Chemistry > Chapter 4: d and f Block Elements > Topic: Actinoids and Comparison of Lanthanoids and Actinoids
Cr (Z=24) has an exceptional configuration (3d⁵ 4s¹) due to the stability of a half-filled 3d subshell, unlike Sc (3d¹ 4s²), Mn (3d⁵ 4s²), or Fe (3d⁶ 4s²).
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Anomalous Properties and Second Period and Chemical Reactivity
Thermal stability of group 15 hydrides decreases down the group due to weaker X-H bonds. BiH₃ (Bi, largest) has the lowest stability among NH₃, PH₃, AsH₃, and BiH₃.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Anomalous Properties and Second Period and Chemical Reactivity
Boiling point increases down group 17 due to stronger London dispersion forces with larger size. I (period 5) has the highest boiling point among F, Cl, Br, and I.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Anomalous Properties and Second Period and Chemical Reactivity
Melting point decreases down group 1 due to weaker metallic bonding. Cs (group 1, period 6) has the lowest melting point among Li, Na, and Cs.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Anomalous Properties and Second Period and Chemical Reactivity
Diagonal relationships minimize electronegativity differences. Be (1.5, period 2) and Al (1.5, period 3) have nearly identical values, unlike other pairs with larger gaps.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Anomalous Properties and Second Period and Chemical Reactivity
Pressure is the correct choice because it does not accurately describe or belong to the category addressed in this question. In the context of Kinetics and Thermodynamic, the other options (Enthalpy, Internal energy, and Volume) are all valid and well-established concepts. Pressure is either unrelated to the topic, describes a different biological process, or represents a common misconception. Questions framed as 'which is NOT' require students to identify the exception among otherwise correct statements, demanding comprehensive knowledge of the topic rather than recognition of a single fact.
Ref: Campbell Biology, Urry et al., 12th Ed.
