text: 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"