Scientists in a lab are working with two different samples of the element mercury. They know that the different samples are different isotopes. Which property of the isotopes must be different?

the mass number

Explanation:

Isotopes are numerous forms of one single element. In simple terms, atomic weights are different for the isotopes. Isotopes refer to the atoms that have the same number of protons but different neutron numbers. The physical properties of the isotopes vary because these properties also based on mass. These variations can be used to distinguish isotopes of an element from each other by applying methods such as fractional distillation and diffusion.

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.