Which of the following statements is true? 1. All isotopes of a given element have the
same mass.
2. The atomic number of an element is the
number of protons in the nucleus of any of its
isotopes.
3. The nucleus of a neutral atom contains
an equal number of electrons and protons.
4. An ion has the same number of protons
and electrons.

the focus of lesson 1 is newton's first law of motion - sometimes referred to as the law of inertia. newton's first law of motion is often stated as. an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

explanation:

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.