None of the above I believe it is what can form a tornado??
Among BF₃, NF₃, OH⁻ and ALCl₃ both NF₃ and OH⁻ acts as a lewis base.
Explaination:
According to lewis theory of acid and base, base is a specie which has either lone pair of electrons or is negatively charged. So, in the given compounds Nitrogen trifluoride contain lone pair of electron on nitrogen and Hydroxide contains a negative charge on oxygen. And botha are capable to donate these electrons to a lewis acid (electrophiles).
The larger the piece the longer it will take to break down. This is because it has more mass that needs to be broken down.
Explanation:
Gases are very less denser also, they've negligible intermolecular force of attraction between the particles of the gas. So, they all are free to roam seperately and hence making a negligible volume for which they become heavy settle down.