Why is nitrogen preferably used in welding process and cooling of substances?

It is an inert gas

The correct answer is 3. It is an inert gas.

Nitrogen is commonly used in welding and cooling processes due to its inert nature. This means that it does not react with other substances, making it ideal for protecting metals from oxidation and other harmful reactions during welding. Additionally, nitrogen's low boiling point (–195.79 °C) makes it effective for cooling substances, particularly for cryogenic applications.

Here's a breakdown of why nitrogen is preferred for these purposes:

1. Inertness: Nitrogen's inertness prevents it from reacting with the metals being welded, preventing oxidation and ensuring the integrity of the weld.
2. Low Freezing Point: Nitrogen's extremely low freezing point makes it a suitable coolant for cryogenic applications, where extremely low temperatures are required.
3. Ease of Handling: As a gas, nitrogen is relatively easy to transport, store, and apply in welding and cooling applications.
4. Non-Toxicity: Nitrogen is non-toxic, making it a safe choice for both the welder and the environment.

While the other options mentioned have some advantages, they are not as relevant to the specific reasons why nitrogen is preferred in welding and cooling processes. For instance, while nitrogen has a low freezing point, it's not the only factor that determines its suitability for cooling. Similarly, while nitrogen is non-toxic, it's not the primary reason for its preference over other gases.

In summary, nitrogen's inertness, low freezing point, ease of handling, and non-toxicity make it an ideal choice for welding and cooling processes.