The gas used for artificial ripening of green fruit is Ethylene.

Explanation:
Ethylene is a natural plant hormone that plays a crucial role in the ripening of fruits. It is widely used in the agricultural industry to artificially ripen green fruits and promote uniform ripening.

Process of Artificial Ripening:
1. Harvesting: Fruits are generally harvested when they are still unripe in order to reduce damage during transportation.

2. Selection: Green fruits are selected for artificial ripening based on their size, shape, and maturity.

3. Ethylene Application: Ethylene gas is used to initiate the ripening process. The green fruits are exposed to ethylene gas in controlled environments such as ripening chambers or rooms.

4. Absorption: Fruits have specific ethylene receptors on their surface, which allow them to absorb the ethylene gas.

5. Ripening: Once the ethylene gas is absorbed, it triggers a series of physiological changes in the fruit, including the breakdown of starches into sugars, softening of the fruit, and development of characteristic color, aroma, and flavor.

6. Monitoring: During the ripening process, the fruits need to be closely monitored to ensure they reach the desired ripeness without overripening or becoming spoiled.

Advantages of Artificial Ripening:
1. Uniform Ripening: Artificial ripening helps to achieve uniform ripening of fruits, ensuring consistent quality and appearance.

2. Reduced Losses: By artificially ripening green fruits, the time between harvest and market availability is reduced, minimizing losses due to spoilage or damage during transportation.

3. Increased Availability: Artificial ripening allows fruits to be made available to consumers throughout the year, even during off-seasons, by accelerating the ripening process.

Ethylene Safety:
While ethylene is generally considered safe for use in artificial fruit ripening, it is important to ensure proper handling and monitoring to prevent excessive exposure. High concentrations of ethylene can lead to overripening, uneven ripening, or undesirable flavor changes in the fruit. Therefore, it is essential to follow recommended guidelines and regulations regarding the use of ethylene for artificial ripening in order to maintain fruit quality and consumer safety.