Mariah the Scientist joins “CBS Mornings Plus” after her new album, “Hearts Sold Separately,” debuted at No. 1 on Billboard’s R&B chart. The singer-songwriter, whose hit “Burning Blue” is Rihanna’s go-to karaoke song, is set to launch a sold-out world tour in January with stops at iconic venues including Radio City Music Hall and the Ryman Auditorium.