php Laravel 9 Undefined variable $questions

I have two tables: Users and Question and I have a form to create questions and an index.blade.php view to show all the questions created. But I have this error, when I want to show the index view with all the questions created:

Undefined variable $questions

This is my UserModel:

protected $fillable = [
    'name',
    'email',
    'password',
];


protected $hidden = [
    'password',
    'remember_token',
    'two_factor_recovery_codes',
    'two_factor_secret',
];


protected $casts = [
    'email_verified_at' => 'datetime',
];


protected $appends = [
    'profile_photo_url',
];

//Relationship onetomany with Questions table
public function questions(){
    return $this->hasMany(Question::class);
}

This is my Question Model:

use HasFactory;

protected $fillable = ['question', 'answer', 'user_id'];

//Relationship with User table
public function user(){
    return $this->belongsTo(User::class);
}

This is my Controller to send the index view which is in a folder called admin, the collection of created questions

public function index()
{

    $questions = Question::all();

    return view('admin.index', compact('questions'));
}

And this is the foreach in the index to show the questions created, the foreach is inside of a table:

@foreach($questions as $question)
    <tr>
        <td>1</td>
        <td>{{$question->question}}</td>
        <td>{{$question->answer}}</td>
    </tr>
@endforeach

And this is the route in web.php

Route::resource('admin/question', QuestionController::class)->middleware('auth')->names('admin.question');