What does "Ｘの一つにＹがある” mean?


I have a sentence in my book like this: 日本が アメリカによく聞かれて困る質問の一つに、”How are you?"
は 日本語で何と言うか、というのがある。

and found a similar example here:
アメリカでは大学への申込の手続きの一つに「なぜＸ大学に行きたいのか」ということに関してエッセイを書くというのがあります。

The part I am confused about is the の一つに... in particular, the に part. Why are
we placing a location particle next to 一つ... shouldn't it just be ｘの一つは （Ｏｎｅ
ｏｆ ｔｈｅ Ｘ）




In Samuel Martin's 1975 _A Reference Grammar of Japanese_ , he calls this use
of `に` the "copula infinitive" (p.396). But more importantly, he glosses it in
English with the word "as":

> うちは **お客様に** 外人の方が多いんで、アスパラガス、ブロッコリーなどの西洋野菜がよくでます。  
>  " **As customers** we have mostly foreigners, so lots of foreign vegetables
> like asparagus and broccoli are out for sale."

He also gives an example that closely parallels yours, using `〜の一つ **に**` ("
**as** one of 〜"):

> **ハワイ群島の一つに** マウイ島がある。  
>  " **As one of the Hawaiian Islands** there is the island of Maui."  
>  = " **Among the Hawaiian Islands** is the island of Maui."

In this example, "among" is a more natural expression in English, but "as one
of" is a little closer to the literal meaning of the Japanese.

As you can see from these examples, `に` isn't really marking a location; it's
functioning adverbially.




In Samuel Martin's 1975 _A Reference Grammar of Japanese_ , he calls this use
of `に` the "copula infinitive" (p.396). But more importantly, he glosses it in
English with the word "as":

> うちは **お客様に** 外人の方が多いんで、アスパラガス、ブロッコリーなどの西洋野菜がよくでます。  
>  " **As customers** we have mostly foreigners, so lots of foreign vegetables
> like asparagus and broccoli are out for sale."

He also gives an example that closely parallels yours, using `〜の一つ **に**` ("
**as** one of 〜"):

> **ハワイ群島の一つに** マウイ島がある。  
>  " **As one of the Hawaiian Islands** there is the island of Maui."  
>  = " **Among the Hawaiian Islands** is the island of Maui."

In this example, "among" is a more natural expression in English, but "as one
of" is a little closer to the literal meaning of the Japanese.

As you can see from these examples, `に` isn't really marking a location; it's
functioning adverbially.

