Answer: Option (a) is the correct answer.
Explanation:
Non-metals are the substances that are deficient in electrons as compared to metals.
For example, carbon, selenium, bromine, chlorine, phosphorous etc are all non-metals.
At room temperature, hydrogen, helium, fluorine, chlorine etc all exist as gases. Whereas some non-metals exist as solid like carbon, phosphorous, sulfur, selenium, iodine etc.
But bromine exist as a liquid.
Hence, we can conclude that the statement Most nonmetals are gaseous, but some are liquid or solid, is true.