Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_21350772_2 (gas_name VARCHAR)
### Question:
What is the 20 year for Nitrous Oxide?
### Answer:
SELECT 20 AS _yr FROM table_21350772_2 WHERE gas_name = "Nitrous oxide"