I left out these sentences which are more or less the same but I need to know which are possible. Thank you very much.

Question

1) I'm the singer in the music (is musical possible?) band The Boyz.
2) I'm the singer in the band, the Boyz.
I'm the singer in the band called the Boyz.
3) I'm the singer in The Boyz band.
I'm the singer of the Boyz band/ in the Boyz music band.
4) I'm the singer in a music group called the Boyz.
I haven't washed the dishes (not just dishes) yet.
5) I still haven't done an art test today.
I haven't had dinner yet today.
I have already done an English test.
6) I haven’t auditioned for a part yet.
I haven’t studied for my history test yet.
7) I haven’t bought a new math (maths) exercise-book yet.
I have already done a lot of sport today.

Answer 1

1) I'm the singer in the band, The Boyz.
Since bands usually play music of some kind, there's no need to use "music."

2) OK

3) None are OK.

4) OK

5) I still haven't taken an art test today.
I haven't had dinner yet today.
I have already taken an English test.

6) Both OK

7) OK
I have already done a lot of exercise today.