Which structure has two or more resonance structures? Select one:
a. NH4+
b.
NO2-
c. CCl4
d.
CO2

b. acid is the correct answer @jayxboof all social media

acid : acids are those which accepts an electron-pairs.

base : bases are those which donates ab electron-pairs.

alkali : it is a base that dissolves in water. it is basically a base and the ph greater than 7.

hydroxide ion : it is a poly-atomic ion which is negatively charged.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.