What I found is that the gum base is made up of plastics and rubbers! then looking at the ingredients for acids this is what I found
PEPSI SUNKIST 7UP MTN DEW
Phosphoric citric and citric acid citric acid
and citric acid ascorbic acid
(ascorbic acid was
only used to keep
Using this data I predict that Pepsi will be the soda able to disolve the gum fastest because it has the most acid that is not used to only preserve.