If two trucks have the same mass, but truck A is traveling 15 km/h, and truck B is traveling 30 km/h, what statement is true. No links or I will report it. This is a science question I just picked chemistry because I didn't know what to pick.

not sure what the statements are but here's what I can tell you

the force of truck b will be greater than the force of truck a

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.