1. 

Lady Gaga collaborated with Ariana Grande on which track...?

2. 

What year did Elton John first meet Eminem?

3. 

Demi Lovato and Christina Aguilera collaborated on which track...?

4. 

How many collaborations have Ed Sheeran and Taylor Swift released?

5. 

Ellie Goulding was the opening act for the North American leg of which Katy Perry tour...?

6. 

What's Adam Levine and Blake Shelton's 'ship' name?

7. 

What TV show did Adam Levine and Blake Shelton first become friends on?