Atoms and Radioactivity (Pre-test)

One of the particles inside the atom is very much lighter than the others. It is the:

• electron.

• neutron.

• proton.

• nucleus.

• I don't know.

The nucleus of the atom contains:

• only neutrons.

• only protons.

• only electrons.

• neutrons and protons.

• I don't know.

An isotope of sodium has 11 protons, 11 neutrons and 11 electrons. Its atomic number is:

• 11

• 22

• 33

• Na

• I don't know.

Different isotopes of the same element contain different numbers of:

• electrons.

• neutrons.

• protons.

• nuclei.

• I don't know.

The element with symbol "He" is:

• hydrogen.

• helium.

• sodium.

• neon.

• I don't know.

Ca is the symbol for:

• calcium.

• calcite.

• copper.

• caesium.

• I don't know.

A proton has the same mass as:

• an atom.

• a neutron.

• an electron.

• a nucleus.

• I don't know.

The half-life of an isotope is 2 years. After two years, what percentage of a sample will be left over?

• 100%

• 75%

• 50%

• 25%

• I don't know.

The element with the atomic number 74 is:

• tungsten.

• arsenic.

• germanium.

• molybdenum.

• I don't know.

All carbon atoms:

• have the same number of protons.

• have the same number of neutrons.

• have the same number of protons and neutrons.

• have different numbers of electrons.

• I don't know.