When an electron from a lower energy d-orbital is excited to a higher energy d-orbital
I. The energy of excitation corresponds to the frequency of light absorbed.
II. This frequency generally lies in the visible region.
III. The colour observed corresponds to the complementary colour of the light absorbed. The above mentioned statements which are correct choose the appropriate option.

Options

A. I and II
B. II and III
C. Only III
D. All of these

Answer

To solve the question, we need to analyze the three statements regarding the excitation of an electron from a lower energy d-orbital to a higher energy d-orbital. Let's break down each statement step by step.

### Step 1: Understanding Electron Excitation
When an electron in a lower energy d-orbital absorbs energy, it can be excited to a higher energy d-orbital. This process involves the absorption of light, which provides the necessary energy for the transition.

**Hint for Step 1:** Remember that electron transitions between energy levels require energy input, typically in the form of light.

### Step 2: Analyzing Statement I
The first statement claims that "The energy of excitation corresponds to the frequency of light absorbed." This is true because the energy (E) absorbed during the excitation is directly related to the frequency (ν) of the light by the equation:
\[ E = hν \]
where \( h \) is Planck's constant. Thus, this statement is correct.

**Hint for Step 2:** Recall the relationship between energy, frequency, and Planck's constant.

### Step 3: Analyzing Statement II
The second statement states that "This frequency generally lies in the visible region." In many cases, the energy differences between d-orbitals in transition metals correspond to the energy of visible light. Therefore, the absorbed frequency often falls within the visible spectrum. This statement is also correct.

**Hint for Step 3:** Consider the typical energy levels of d-orbitals in transition metals and their relation to visible light.

### Step 4: Analyzing Statement III
The third statement asserts that "The colour observed corresponds to the complementary colour of the light absorbed." This is a well-known principle in color theory. When a substance absorbs certain wavelengths of light, the color that we perceive is the complementary color of the absorbed light. This statement is correct as well.

**Hint for Step 4:** Think about how colors work in terms of absorption and perception.

### Conclusion
Since all three statements are correct, the appropriate option would be the one that states that all of these statements are correct.

**Final Answer:** All statements (I, II, and III) are correct.