In which type of chemical reaction would two reactants join together and form one product

Synthesis Reaction

Explanation:

A synthesis reaction occurs when two or more reactants combine to form a single product. In a decomposition reaction, one reactant breaks down into two or more products. This is the reverse of a synthesis reaction. Replacement reactions occur when elements switch places in compounds.

the atomic mass is the bottom number on the element.

-steel jelly

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.