Answer:
They all have the same number of protons but different numbers of neutrons.
Explanation:
Elements will always have the same number of protons no matter the isotopes. Isotopes only change the number of neutrons. Silicon will always have 14 protons. So silicon-28 has 14 protons and 14 neutrons. Silicon-29 has 14 protons and 15 neutrons. Silicon-30 has 14 protons and 16 neutrons.
Colligative properties are those substances that depend
on the number of substances in the solution, not in the identity of that
substance. The property changes the way that it does when the amount of solute
is increased because it enables the solute to be scattered more. For example,
the freezing point of salt water is lower than that of the pure water due to
the salt ions present in water.