HELP ASAPPP An iron nail was placed in an open test tube containing some salt solution, and then left for a week for observations. The experimental setup and observations are shown below.

Which of the following best demonstrates that a chemical change has taken place?

The salt solution was discolored after a week.

The volume of the salt solution has decreased.

The mass of the salt solution, beaker and nails decreased.

The iron nail is still undissolved in the solution after a week.

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.