Energy in an ecosystem flow from consumers to producers.

False

Explanation:

Producers are organisms that are capable of synthesizing organic molecules from simple inorganic materials such as water, CO2 and SO2.

Every other living organisms  that cannot produce their own food are referred to as consumers. All consumers in an ecosystem depend directly or indirectly on the producers for their feeding.

Hence, energy always flow from producers to consumers in an ecosystem.

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.