Which among the four `chi` versus T graphs shown in the following figure is the correct one for a paramagnetic substsnace will look like ?

Options

A.
B.
C.
D.

Answer

To determine the correct susceptibility (χ) versus temperature (T) graph for a paramagnetic substance, we can follow these steps:

### Step 1: Understand the relationship between susceptibility and temperature for paramagnetic substances.
- For paramagnetic materials, the susceptibility (χ) is inversely proportional to the temperature (T). This means that as the temperature increases, the susceptibility decreases.

### Step 2: Analyze the behavior of susceptibility with temperature.
- As temperature (T) increases, the thermal agitation of the magnetic dipoles in the paramagnetic material increases, which leads to a decrease in the alignment of these dipoles. Consequently, the susceptibility (χ) decreases.

### Step 3: Identify the correct graph.
- Given the inverse relationship, the graph of susceptibility (χ) versus temperature (T) should show a downward trend as temperature increases. This means that the graph should slope downwards from left to right.

### Step 4: Compare the provided graphs.
- Look at the four graphs provided in the question. The correct graph will show a clear decrease in susceptibility as temperature increases.

### Step 5: Select the correct option.
- After analyzing the graphs, the third option is the one that correctly represents the inverse relationship between susceptibility and temperature for a paramagnetic substance.

### Final Answer:
- The correct graph for a paramagnetic substance showing the relationship between susceptibility (χ) and temperature (T) is option number 3.

---