Who believed that atoms of a given element are identical

How have the greenhouse gasses increased from the year 2000 to 2018

Which sentence about particles in matter is true? a. atoms are present in solids and liquids but not in gases. b. the particles of matter are in constant motion. c. the same kinds of atoms are found in different elements. d. when a solid changes to a liquid, the sizes of the particles change.

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.