Answer:
Two common properties of iron, water, and air are:
1. They are all matter: Iron, water, and air are all forms of matter. Matter is anything that has mass and occupies space.
2. They are all composed of atoms: Iron, water, and air are all made up of atoms. Iron is composed of iron atoms (Fe), water is composed of hydrogen and oxygen atoms (H2O), and air is composed of a mixture of different gases, primarily nitrogen (N2) and oxygen (O2), along with trace amounts of other gases.