<span>Physical properties are easier to observe than chemical properties as they include characteristics such as color, texture, etc. while to observe chemical properties, testing must be done of the substance such as heating the substance up to determine at what temperature it will combust</span>
Explanation: Physical Properties are the properties which can be observe through naked eyes.
Chemical properties are the properties which induces any chemical change in the identity of the molecule.
Physical properties include color, smell, texture etc which can be easily observed but chemical properties include mass, volume reactivity which can only be observed when any changes in the chemical identity of the substance takes place.
Argon-40 because it is the isotope with the closest mass to the atomic mass of the element. Making it more stable than the others allowing it to be the most abundant in nature.
