Which type of property of matter can be observed without changing the composition of the substance?

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

In the particles are arranged in a regular, repeating pattern. a)a crystalline liquid b)a crystalline solid c)all gases d)all solids

Apiece of metal with a length of 1.42 cm was measured using four different instruments. which of the following measurements is the most accurate?