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_name_90 (chemical_class VARCHAR, example VARCHAR)
### Question:
Which chemical class uses the example Chloroethane (ethyl chloride)?
### Answer:
SELECT chemical_class FROM table_name_90 WHERE example = "chloroethane (ethyl chloride)"