Which of the following pair of transitional elements exhibit highest and lowest density

Options

A. Os and Sc
B. Os and Pt
C. Hg and Sc
D. Os and Ir

Explanation

To determine which pair of transition elements exhibits the highest and lowest density, we can follow these steps:

### Step 1: Identify the Transition Elements
We need to identify the transition elements mentioned in the options provided. The pairs given are:
1. Osmium (Os) and Scandium (Sc)
2. Osmium (Os) and Platinum (Pt)
3. Mercury (Hg) and Scandium (Sc)
4. Osmium (Os) and Iridium (Ir)

### Step 2: Determine the Oxidation States
Next, we need to consider the highest oxidation states of the elements in each pair:
- **Osmium (Os)**: Highest oxidation state is +8.
- **Scandium (Sc)**: Highest oxidation state is +3.
- **Platinum (Pt)**: Highest oxidation state is +8.
- **Mercury (Hg)**: Highest oxidation state is +4.
- **Iridium (Ir)**: Highest oxidation state is +8.

### Step 3: Compare Densities
Now, we need to compare the densities of the elements:
- **Density of Osmium (Os)**: Approximately 22.59 g/cm³ (one of the densest elements).
- **Density of Scandium (Sc)**: Approximately 2.99 g/cm³ (much less dense).
- **Density of Platinum (Pt)**: Approximately 21.45 g/cm³.
- **Density of Mercury (Hg)**: Approximately 13.53 g/cm³.
- **Density of Iridium (Ir)**: Approximately 22.56 g/cm³.

### Step 4: Identify Highest and Lowest Density
From the densities:
- The highest density is exhibited by **Osmium (22.59 g/cm³)**.
- The lowest density is exhibited by **Scandium (2.99 g/cm³)**.

### Conclusion
The pair of transition elements that exhibit the highest and lowest density is:
- **Osmium (highest density) and Scandium (lowest density)**.

### Final Answer
**Osmium and Scandium exhibit the highest and lowest density, respectively.**

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