15 Answer:
According to modern atomic theory, _____ can't move from one energy
level to another.
16 Answer:
Quarks make up all the known particles of the nucleus.
a. true
b. false
17 Answer:
A weak force "glues" protons together in the nucleus.
a. true
b. false
18 Answer:
Electromagnetic force is the force of attraction which exists between
all objects.
a. true
b. false
19 Answer:
Particles smaller than an atom are called subatomic particles.
a. true
b. false
20 Answer:
The atomic mass of an element never changes.
a. true
b. false

According to modern atomic theory, proton can't move from one energy level to another but the electron move from one energy level to another energy level when the energy is absorbed.

Quarks make up protons and neutrons that make up an atom's nucleus. Each proton and each neutron contains three quarks. The particle that carries the strong force is called a gluon, so-named because it so tightly "glues" quarks together into larger particles. Electromagnetic force is the force of attraction that is present between all objects. This force of attraction make them attached to one another.

Subatomic particles are electrons which is negatively charged and the positively charged protons and the electrically neutral neutrons.

An elements atomic number will never change but atomic mass can change that we call these isotopes. The atomic mass is the sum of the protons and neutrons in the nucleus. In an isotope you have more neutrons than you have protons.

So we can conclude that proton, true, true, true and false are the answers of the given questions.

Learn more about atomic mass here: https://brainly.com/question/338808

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