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 (lifetime__years_ VARCHAR, chemical_formula VARCHAR)
### Question:
What is the lifetime (years) for chemical formula ch 4?
### Answer:
SELECT lifetime__years_ FROM table_21350772_2 WHERE chemical_formula = "CH 4"