The noun form of the adjective 'opaque' is opaqueness.
Opaque can be used as an adjective and a noun.
Aluminum foil is opaque.
No. Clarity is the noun form of clear. The opposite of clarity is obscurity, or opacity if you're referring to something opaque.
Opaque
more opaque [comparative] most opaque [superlative]
"opaque"
There are many objects that no light can pass through, although of course, it depends on what type of light you're talking about. The name of the type of object that visible light cannot pass through is called opaque.
Yes, a carpet is opaque.
Opaque
Opaque
"opaque"
paper is opaque