laravel 5.6 bulk inserting json data

Based on your sample data, you can json_decode the data and then use a single Model::insert():

{
  "data":[
    {
      "paper_id":"5",
      "question_no":"2",
      "question":"test insert code",
      "answer1":"answer1",
      "answer2":"answer2 ",
      "answer3":"answer3 ",
      "answer4":"Answer4 ",
      "answerC":"Correct Answer",
      "knowarea":"who knows!"
    },
    ...
  ]
}

// Controller.php
public function store($json)
{
    $data = json_decode($json, true);
    Paper::insert($data);
}

That will create arrays from your json and then insert all the records at once.