Iron-59 has a half-life of 44 d. If a nuclear laboratory receives a sample of 32 µg (microgram) of iron-59, how many micrograms of iron-59 remain after 176 d?

Astable electron arrangement for an atom is one that does not easily change. how is this arrangement arrived at? a. valence electrons are transferred or shared to create a full outer shell of electrons. b. valence electrons are discarded into space to create a full outer shell of electrons. c. protons (positive charge) pair with valence electrons (negative charge) to create a strong bond. d. outer shells with valence electrons are transferred or shared.