Question

which is not a \green\ option in the chemical industry?
supercritical carbon dioxide
using the least - expensive organic solvent
using water
solventless reactions

Explanation:

Green chemistry aims to reduce or eliminate the use and generation of hazardous substances. Supercritical carbon - dioxide is a non - toxic, non - flammable, and environmentally friendly solvent. Water is a benign and abundant solvent. Solventless reactions reduce the use of solvents, which are often harmful. Using the least expensive organic solvent may not necessarily mean it is environmentally friendly as many inexpensive organic solvents can be toxic or have high environmental impact.

Answer:

Using the least expensive organic solvent