How are positive ions formed?

Positive ions, also known as cations, are formed when a metal atom loses one or more of its electrons. This loss of negatively charged electrons leaves the atom with a net positive charge because the number of protons (which are positively charged) remains unchanged. As a result, the overall charge becomes positive since there are now more protons than electrons. This process is fundamental in the formation of metallic bonds and the behavior of metals in chemical reactions.

The other scenarios involve non-metals or changing the number of protons, which do not lead to the formation of positive ions. Non-metals typically gain electrons to form negative ions (anions) rather than losing them. Additionally, gaining or losing protons alters the identity of the element rather than creating a simple ion, making those options incorrect in the context of how positive ions are formed.