.net core serialize object to json Edit

How do I serialize a list of objects to json in .Net code. I have a list of countries with properties Id, Code & Name. I want to serialize the list to json.

public class Country
{
    public int Id { get; set; }
    public int Code { get; set; }
    public String Name { get; set; }
}

If using .Net Core 3.0 or later you can use the default built in System.Text.Json parser

using System.Text.Json;

List<country> lstCountries = new Country().Get();
String countryJson = JsonSerializer.Serialize(lstCountries);

Here is the serialized JSON code.

[{"Id":1,"Code":91,"Name":"India"},{"Id":2,"Code":86,"Name":"China"},{"Id":3,"Code":1,"Name":"USA"},{"Id":4,"Code":91,"Name":"India"},{"Id":5,"Code":7,"Name":"Russia"},{"Id":6,"Code":91,"Name":"India"},{"Id":7,"Code":86,"Name":"China"}]