what substances play an important role in communication between cells in a multicellular organism by acting as a chemical message

The correct answer is - ligands such as hormones and neurotransmitters.

Explanation:

Communications between the cells of the unicellular organisms take place by the chemical signaling and the substances that help in sending chemical signals between cells are called ligands.

A ligand is a chemical molecule that binds with a specific molecule or a specific signaling receptor, a protein in or on the target cell. Hormones and neurotransmitters are the ligands that help in cell signaling and send chemical messages to the target sites.

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation:

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).