Physics Physics Nuclear Physics

Question 1

What particles make up the atomic nucleus?

Accepted Answer

Protons and neutrons

Answer

The atomic nucleus is composed of protons (positively charged) and neutrons (neutral), collectively called nucleons.

Question 2

The atomic number of an element equals the number of:

Accepted Answer

Protons in the nucleus

Answer

The atomic number (Z) equals the number of protons in the nucleus and uniquely determines the chemical identity of an element.

Question 3

Isotopes of an element have the same number of protons but different numbers of:

Accepted Answer

Neutrons

Answer

Isotopes are atoms of the same element with the same atomic number but different numbers of neutrons, giving them different mass numbers.

Question 4

What force holds protons and neutrons together in the nucleus?

Accepted Answer

Strong nuclear force

Answer

The strong nuclear force holds nucleons together in the nucleus, overcoming the electromagnetic repulsion between the positively charged protons.

Question 5

The mass number of an atom equals:

Accepted Answer

Number of protons plus neutrons

Answer

The mass number (A) is the total count of nucleons — protons plus neutrons — in an atom's nucleus.

Physics Practice Test