Answer:
Ca2+ is an ion with a correct charge.
Here's 2 links that hopefully helps you:
https://science.howstuffworks.com/innovation/scientific-
experiments/scientific-method9.htm
https://ask.metafilter.com/152401/How-does-the-idea-of-the-scientific-method-inform-our-modern-culture-and-life
The magnetic field of an electromagnet disappears as soon as current is turned off.
K2CO3 can be thought to contain 6 atoms (2 K, 1 C, 3O).
If you are given grams of K2CO3 you can divide by the molar mass to get to moles and then multiply by Avogadro's number.
