21. As an example, free Benzene is extremely unreactive in cycloadditions due to its aromaticity. 22. A container molecule could encapsulate a guest molecule and thus subsequently renders the guest unreactive . 23. The oxides HfO 2 are white solids with high melting points and unreactive against most acids. 24. It is a colorless, non-polar molecule, nearly unreactive except when it burns. 25. There is a residue of unreactive tarry compounds mixed with ash from the coal and catalyst. 26. For example, unreactive gases ( e . g . noble gases ) formed one column. 27. Additionally, gold is extremely unreactive , hence it does not tarnish or corrode over time. 28. The presence of a strong triple covalent bond in the molecule renders it unreactive under normal circumstances. 29. These oxides of Ca, Al, K, and Si are unreactive to reduction by the hydrogen. 30. Though SO 2 too passes through the tower it is unreactive and comes out of the absorption tower.