Which of the following elements shows maximum number of different oxidation states in its compounds ?
(a)Eu
(b)La
(c)Gd
(d)Am

Options

A. Eu
B. La
C. Gd
D. Am

Explanation

To determine which of the given elements shows the maximum number of different oxidation states in its compounds, we will analyze each option based on their known oxidation states.

### Step 1: Analyze Europium (Eu)
- Europium primarily exhibits oxidation states of +2 and +3.
- It does not show a wide range of oxidation states.

**Hint:** Look for the common oxidation states of each element.

### Step 2: Analyze Lanthanum (La)
- Lanthanum typically shows an oxidation state of +3.
- Similar to Europium, it does not exhibit multiple oxidation states.

**Hint:** Consider the stability of the oxidation states for lanthanides.

### Step 3: Analyze Gadolinium (Gd)
- Gadolinium can exhibit oxidation states of +2 and +3.
- Like Europium and Lanthanum, it does not show a wide variety of oxidation states.

**Hint:** Check if the element has a stable electron configuration that limits its oxidation states.

### Step 4: Analyze Americium (Am)
- Americium can exhibit multiple oxidation states: +2, +3, +4, +5, and +6.
- The larger size and lower ionization energy of Americium allow it to lose electrons more easily, leading to a greater variety of oxidation states.

**Hint:** Consider how the atomic size and ionization energy influence the number of oxidation states.

### Conclusion
Among the given options, Americium (Am) shows the maximum number of different oxidation states in its compounds, specifically +2, +3, +4, +5, and +6.

**Final Answer:** (d) Am