1. whereNull

query

                    select * from `users` 

                          where `email_verified_at` is null
                    

using model

                    $users = User::select("*")
                        ->whereNull('email_verified_at')
                        ->get();

                          

2. whereNotNull

query

                          select * from `users` 

                                where `email_verified_at` is not null
                          

using model

                          $users = User::select("*")
                        ->whereNotNull('email_verified_at')
                        ->get();