Hi Jay and Drew,
becomes quell' in front of vowels: quell'altro, quell'orso, quell'enunciato.
This is called elision (elisione) and it requires an apostrophe.
Quale and qual are independent words. The -e in quale is cut through apocope (troncamento), so there's no apostrophe involved.
It's either quale è or qual è, quale era or qual era.
Apocopes are also presents in words like buono/buon or grande/gran.
Its plural form, quali, gets the apostrophe because there's an elision involved: quali erano > qual'erano (although this is rare, normally you would use quali erano if no particular writing style is involved).
I hope this makes sense! It's a tricky question for natives too.
Qual'è is a mistake, but it's still widely used. My high school Italian teacher once said that, if we really needed to put an apostrophe there, we might as well put five, as in qual'''''è. It eventually stuck that we had to put none because we would associate it with that funny writing.
Hope this helps!