posted by ray .
Isotopes (select one or more):
are chemicals that react only with protons.
for an element have the same chemical properties.
are atoms of an element that differ in the number of protons.
are atoms of an element that differ in the number of neutrons.
for an element are equal in frequency.
1. Do not react with protons.
2. Have the same chemical properties (but usually different physical properties).
3. Do not differ in the number of protons.
4. Differ in the number of neutrons.
5. Has nothing to do with frequency.