Because without them, the residual oil of the surface of crisps would react with oxygen from the air and give them a stale flavour.
Bags are filled with nitrogen, either pure or mixed with carbon dioxide, not so much to keep them inflated (that could be done with air), but to displace the oxygen, which would cause the oils to go rancid.Carbon dioxide is also used sometimes,
nitrogen
onion
The word that is wrong is 'were'The reason that it is wrong is that the subject of the sentence 'A packet of crisps' is singular (it refers to one packetnot the many crisps in the packet) while the verb 'were found' refers to the plural (i.e they were found). As there is only one packet of crisps 'was found' the singular should be used (i.e. it was found). The sentence should therefore read:-"A packet of crisps was found on the bench."
The collective noun for crisps is a packet of crisps.
You remember then crisps called Cheetahs? There's your answer.
can I take sweets and crisps to Ausrtalia..Sydney
packet of crisps weight = weigh of a crisp * number of crisps
hisfavorite crisps are pomybears
the porpose of the walkers crisps business
Crisps are normally made from potatoes