Pronoun (indefinite)- fill in the blanks - advanced

it / which / what / nothing / something / one

1. He was obsessed with the project and wanted to be perfect.
2. Katherine Mansfield is of the best short story writers of all time.
3. The palace,  was designed to entertain visiting dignitaries, was destroyed in World War Two.
4. How was that no one had ever heard of this woman?
5. The valley, is known as Harting Combe, is beautiful.
6. First the lights went out and then else happened.
7. The director was at the screening of the film during  half the audience walked out.
8. He forgot he was meant to do.
9. He found too painful to speak about.
10. The public knew at all about what had really happened.
11. The book, in details of the expenses scandal emerge, was an international bestseller.
12. The road, is steep, affords beautiful views of the Hampshire countryside.
13. The Burj Khalifa in Dubai is 828 m high, is the current world record.