Transition metals have characteristic physical and chemical properties that distinguish them from main-group metals, such as those in Group 1. Iron is a transition metal. Which of the following statements correctly describes iron?
A metal with a high density that can form ions with different charges, such as Fe2+\text{Fe}^{2+}Fe2+ and Fe3+\text{Fe}^{3+}Fe3+.
A metal that reacts vigorously with cold water to produce hydrogen gas.
A soft metal with a very low melting point that can be easily cut with a knife.
A metal with a very low density that floats on water.