An atom that has only one electron in its valence electron shell is chemically reactive?

The valence electrons are the electrons in the outermost electron shell of an atom.

The number of electrons in an atom's outermost valence shell governs its bondingbehaviour.

That is why elements whose atoms have the same number of valence electrons are grouped together in the Periodic Table.

Generally, elements in Groups 1, 2, and 13 to 17 tend to react to form a closed shell, corresponding to the electron configuration s2p6.

This tendency is called the octet rule, because the bonded atoms have eight valence electrons.

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force