"Are those a new [object]?"

Question

Is this question grammatical:

Are those a new [object]?

I know that the singular form of that question, "Is that a new [object]?", sound perfectly fine but the collective form of it sounds odd, at least for me?

Answer 1

Skip the indefinite article 'a', and you're set.

Are those new shoes?

For collectives, use the singular as you normally would in a non-question.

Is that a new solar system?

Is that a new set of planets?

Are those new planets?

Answer 2

First, a basic grammatical point. Copular verbs like be don't have objects. The words that follow them form the complement or, more precisely, the subject predicative.

The normal patterns are, to continue the interrogative construcion:

Is that a new hat?

and

Are those new shoes?

However, it is just about possible to imagine a native speaker saying:

Are those a new pair of glasses?

Here the plural form of glasses overrides the singular form of a new pair.