Adsorption of `N_(2)` gas on iron at 83 K is ………. Whereas at 773 K, it is …….(fill in the type of adsorption).

Explanation

To determine the type of adsorption of \( N_2 \) gas on iron at different temperatures, we need to analyze the conditions given:

1. **At 83 K**:
- At this low temperature, the adsorption process is likely to be **physisorption**. Physisorption occurs at low temperatures and involves weak van der Waals forces. Since \( N_2 \) is a stable molecule with a strong triple bond, it will not ionize or undergo significant changes at this temperature. The interaction is primarily due to physical forces, making it physisorption.

2. **At 773 K**:
- At this high temperature, the adsorption process is likely to be **chemisorption**. Chemisorption involves the formation of strong chemical bonds between the adsorbate and the surface. At elevated temperatures, \( N_2 \) can ionize and form new substances (like NO), indicating a chemical reaction with the iron surface. Therefore, the adsorption at this temperature is chemisorption.

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