This is my code:-

```
List<JObject> students =[{"id":"101","name":"one","parent_id":"1"},{"id":"102","name":"two","parent_id":"2"},{"id":"103","name":"three"},{"id":"104","name":"four"}];

```

I tried the following code using Linq but not working

```
List<JObject> newStudents = students.Where(x => x.Property("parent_id").ToString() == null).ToList();

List<JObject> existedStudents = students.Where(x => x.Property("parent_id").ToString() != null).ToList();

```

In the above list contains 4 objects , first two objects contains `parent_id` key next two objects doesn't contain. How to `parent_id` key existed and not existed list in c#.