CREATE TABLE table_59221 ("Physical property" TEXT, "Helium" TEXT, "Neon" TEXT, "Argon" TEXT, "Krypton" TEXT, "Xenon" TEXT)

which Helium has a Argon of 189.6?
SELECT "Helium" FROM table_59221 WHERE "Argon" = '−189.6'
SELECT "Helium" FROM "table_59221" WHERE "Argon" = '−189.6'