One of - singular/plural dilemma

[anushreevarma]

I am having a hard time understanding when to use singular verb versus plural verb for questions of the kind
One of the (X) that (Y)

For a sentence like :-
One of the shirts that belongs to him was stolen.

If I understand the rules correctly, if there is a "that" in a sentence of type One of the (X) that (Y), the verb should be plural. So in the above case is belong the right word?
Belongs is what I thought was right here.
I am confident that was is the right word for the last phrase.
Can you please clarify when should a singular verb be used in the case above. I keep getting these One of questions wrong all the time.
Thanks!

[mschwrtz]

Here's the correct form

One of the shirts that belong to him was stolen.

Let's start with the more straightforward of these verbs, the was. Strip out the relative clause that belong(s) to him to see

One of the shirts... was stolen.

Heck, strip out the prepositional phrase of the shirts to see

One... was stolen.

So yes, was is the correct verb.

Now, that relative clause we took out in the first place, that belong(s) to him, modifies the noun shirts, and so the verb in that clause should agree with shirts. So,

...the shirts that belong to him...

A verb must agree with the subject of its own clause, which may not be the subject of the sentence.
.

[JbhB682]

Here's the correct form

One of the shirts that belong to him was stolen.

Now, that relative clause we took out in the first place, that belong(s) to him, modifies the noun shirts, and so the verb in that clause should agree with shirts. So,

...the shirts that belong to him...

A verb must agree with the subject of its own clause, which may not be the subject of the sentence.
.

Hi Experts -- for the relative clause [that belong (s) to him] specifically

-- How do you know if the relative clause modifies the noun
i) shirts

AND NOT the noun
ii) "One" (at the beginning of the the sentence) ?

Is it perhaps, all the shirts "belong to him"

If the relative clause was referring to "One", we would have to assume that the author has only ONE shirt that belongs to him

[esledge]

The default is that “that” refers to the noun right before it, unless there is a compelling reason to think otherwise. (Same for “which” and other “wh-“ relative clauses.) For example:
The portrait of the queen that is hanging in the main hall was painted in 1842.

(1) Logically, the queen is not hanging in the main hall. And if she were, “who” would be used instead of “that.”
(2) While they generally should touch, “that is hanging” and “portrait” can be separated by a short, necessary modifier such as “of the queen.” This is an acceptable exception.

Turning back to:
One of the shirts that belong to him was stolen.
(1) “shirts that belong” is not a silly meaning, so go with the default understanding of the "that" modifier.
(2) If you actually did want to modify “one,” you’d have to rearrange the sentence:

Of the shirts, one that belongs to him was stolen. (Different meaning: lots of shirts exist, but one of his was stolen.)