what is the main difference between a physical reaction and a
chemical reaction?

physical reactons dont change the substance

Explanation:

physical changes are things like shape and color it doesnt change the base material but a chemical change changes the base aterial baking soda and vinegar create co2 but cutting wood still results in wood hope this helps god bless

1 a

2 d

3 a

4 c

explanation:

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.