A constant question.

Is the 에 in 어디에 usually not very pronounced when said aloud? I feel like I've never heard 어디에 있어요 syllable for syllable, it usually sounds like 어디 있어요

What is the difference between 안경은 어디에 있습니다? (which is marked incorrect) and 안경이 어디에 있어요? (which is marked correct)? The only difference I can see is the formality of the first. At my level of understanding, they both appear to be grammatically proper. Or is the difference the "the" in the translation provided, if it corresponded better to the subject particle than the topical particle?