While or when?

I was having lunch __________ James arrived and we had to go.

• when

• while

__________ I heard the doorbell, I went to the door.

_________ Jo was washing her hair, I did my homework.

• when

• while

__________ I am buying the bread, you can go to the butcher's.

• when

• while

I was at the baker's __________ I met Jo.

The customer was being helped by the salesman __________ the thief came into the store.

• when

• while

__________ you saw Keith, was he with Jo?

• when

• while

I was in the shop __________ someone stole my bag.

• when

• while

I hurt my back ____________ I tried to lift the piano.

• when

• while

__________ we were standing outside the cinema, someone picked my pocket.