An unknown substance in aqueous solution is treated with various reagents including hexane, a colorless liquid less dense than water. The test tube is stoppered and shaken. The upper layer remains colorless. name two nometal species that cannot be present in the unknown

Chlorine and bromine

Explanation:

The chlorine and bromine in the answer may in form of chlorine water solution or bromine water solution.

When halogen generally are tested with hexane, it gives a characteristic colour. The color of chlorine is yellowish green. But with a greenish tinge and the color of bromine reddish but with an orange tinge. Iodine gives violent colour.