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_98 (sodium VARCHAR, rubidium VARCHAR)
### Question:
what is the properties of sodium when rubidium is nacl (2.1)?
### Answer:
SELECT sodium FROM table_name_98 WHERE rubidium = "nacl (2.1)"