Answer is: 7. Lewis base. Nitrogen trifluoride (NF₃) <span>a Lewis base, because it can donate its </span>lone pair<span> of electrons (lone pair of electrons are in nitrogen atom). </span>Lewis base <span>is any species that has a filled orbital containing an </span>electron pair<span> which is not involved in </span>bonding<span> but may form a dative bond with a Lewis acid. </span>Nitrogen-fluorine<span> compound is a colorless, odorless and nonflammable gas.</span><span>
By adding a surface that increases friction? Such as outdoor mats(rough ones), which increases friction between the bottom of the boots and the surface.
