Find the statement which is not correct with respect to transition metals

Options

A. Most transition metals, should on thermodynamic consideration liberate hydrogen from acids.
B. The colour of the hydrated ions is due to transition of electrons from different 'd' orbitals of the same principle quantum numbers
C. The compounds of the elements in low oxidation states are generally ionic.
D. The complex formation of transition metal ions is often accompanied by a change of colour and sometimes by a change in the intensity of the colour

Answer

To find the statement which is not correct with respect to transition metals, we need to analyze each of the four statements given in the question.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "Most transition metals should on thermodynamic consideration liberate hydrogen from acids."
- This statement suggests that transition metals can react with acids to liberate hydrogen gas. However, this is not true for many transition metals because they often form a passive oxide layer that makes them less reactive. Additionally, many transition metals have a positive reduction potential, meaning they cannot reduce hydrogen ions to hydrogen gas. Therefore, this statement is incorrect.

- **Statement 2**: "The color of hydrated ions is due to transitions of electrons from different d orbitals of the same principal quantum numbers."
- This statement is true. The color observed in transition metal complexes arises from d-d transitions, where electrons move between d orbitals split by the ligand field, leading to the observed colors.

- **Statement 3**: "The compounds of elements in low oxidation states are generally ionic."
- This statement is also true. Compounds with transition metals in lower oxidation states tend to be more ionic because there is a more complete transfer of electrons from the metal to the anion.

- **Statement 4**: "For the complex formation of transition metal, it is often accompanied by a change of color and sometimes by a change in the intensity of the color."
- This statement is true as well. Complex formation involves d-orbital splitting, which can lead to changes in color and intensity due to the transitions of electrons.

2. **Conclusion**:
- After analyzing all four statements, the incorrect statement is **Statement 1**: "Most transition metals should on thermodynamic consideration liberate hydrogen from acids."

### Final Answer:
The statement which is not correct with respect to transition metals is: **"Most transition metals should on thermodynamic consideration liberate hydrogen from acids."**