Among the following metals, the most dense is :

Options

A. Osmium
B. Chromium
C. Platinum
D. Gold

Answer

To determine which of the given metals is the most dense among osmium, chromium, platinum, and gold, we will follow these steps:

### Step 1: Understand Density
Density is defined as mass per unit volume. The formula for density (D) is:
\[ D = \frac{m}{V} \]
where \( m \) is mass and \( V \) is volume.

### Step 2: Identify the Metals and Their Atomic Numbers
The metals we are comparing are:
- Chromium (Cr) - Atomic number 24
- Osmium (Os) - Atomic number 76
- Platinum (Pt) - Atomic number 78
- Gold (Au) - Atomic number 79

### Step 3: Analyze the Periodic Trends
- Chromium has the lowest atomic number among the four metals, which suggests it has a lower density compared to the others.
- Osmium, platinum, and gold are in the same period (6th period) and have higher atomic numbers.

### Step 4: Consider Atomic Structure and Density Trends
In general, as we move across a period in the periodic table:
- The atomic mass increases, but so does the volume due to the increase in the number of electron shells.
- The increase in volume can outpace the increase in mass, which can lead to a decrease in density.

### Step 5: Compare the Densities of Osmium, Platinum, and Gold
- Osmium is known to have a very high density, even higher than that of gold and platinum.
- Gold is also dense but typically less dense than osmium.
- Platinum is denser than chromium but less dense than osmium and gold.

### Step 6: Conclusion
Based on the trends and known densities of these metals:
- The order of density from highest to lowest is:
1. Osmium
2. Gold
3. Platinum
4. Chromium

Thus, the most dense metal among the options provided is **osmium**.

### Final Answer
The most dense metal among the given options is **osmium**.

---