Bread or cake flour?
I have a tupperware container of flour in my cabinet and I don't remember what it is. It's either bread flour or cake flour. Any way to tell without ruining a recipe?
Cake flour is almost always bleached, and is more likely to be lumpy. Do you have any AP to compare it to?
It's more likely bread flour, because that is sold in bags. Cake flour usually comes in 2 lb boxes (with liner).
You are more likely to have transferred bread flour to a tupper than cake flour.
And as other have written, cake is more likely to be bleached.
Bread flour is a bit darker than cake flour or all purpose flour. There are recipes you can make with either/or - so I would use it for those and buy a new batch if your are making something specific.
Cake flour is much finer, but it may be difficult if you have no experience. (e.g.: it is easy for me to say a wolf has a larger head than a dog, but it is not useful if you have never seen a wolf or a dog).