How many neutrons does calcium have?
In calcium-40, there are 20 neutrons.
It depends on the isotope.
Calcium's atomic number is 20, which means all calcium atoms have 20 protons in their nuclei. However, the number of neutrons in the nuclei of the calcium atoms can vary. Atoms of the same element with different numbers of neutrons are isotopes.
There are many isotopes of calcium, ranging from calcium-40 with 20 neutrons, to calcium-48 with 28 neutrons.
For more on the isotopes of calcium, refer to the following website. https://en.m.wikipedia.org/wiki/Calcium