ANSWER:

Your arms should not be uncovered if you are wearing proper sleeves! You must cover that area well so that it is not exposed when you bow or prostrate and you also must cover the area under your chin to the best of your ability.

You say we have to cover the area between our our chin and start of our neck when reading Salaah or in front of non-mahrams, but before I read my salaah I wear an under cap then I put over a long burqa (khimar) and that part under the chin still becomes under covered. Almost the entire salaah, it distracts me as I have to keep covering it. This also exposes my the skin of my arms as I try to cover