how and why is it like this?

2. Both previous answers are wrong. Light and heat have mass according to Einstein's famous formula E=mc^2: mass is energy and every energy has a corresponding mass. Believe it or not but heated object weigh just a tiny-winy more than unheated, just because c^2 is a HUUUUGE number. And photon (the particle of light) also has mass and even is deflected by Sun (that was measured) and galaxies around us (gravitational lenses).

3. These element are unstable, they easily broke into parts and these parts are different elements. In some cases scientists were able to obtains only few dozen atoms of these artificially created elements. And experiments in which these elements are created (collision of other atoms) require these atoms to move at huge speed. So it is difficult to say if these elements will condense into liquid or solid phase when cooled to room temperature.

Air contains protons and neutrons they have mass so air is matter. Heat and light have no matter so they are not mass. Those elements were too unstable to exist for more than a second.

1)air consist of particles

2)heat and light IS NOT matter, and they dont have mass too, they are just a sorce of energy

3)STATE of matter, that means for example water evaporating into gas, which you cant say that the water is gone, it just changes the state. i hope that helps