Here's the passage with the correct answers selected, along with explanations for each choice:

Almost a hundred thousand people were killed (1) **and** half a million homes destroyed as a result of an earthquake in Tokyo in 1923. The earthquake began a minute before the noon (2) **when** inhabitants of Tokyo were cooking their midday meals. Thousands of stoves (3) **were** overturned soon as the earth began to shake. As a result, small fires broke out everywhere and quickly spread. The fire engines were prevented from going to help because many of the roads had cracked open. It was impossible (4) **to use** fire fighting equipment as most of the water pipes burst. Consequently, over ninety percent (5) **of** the damage was caused by fire rather (6) **than** by the collapse of the buildings.

1. **and**: The conjunction "and" correctly connects two related clauses: "Almost a hundred thousand people were killed" and "half a million homes destroyed."
2. **when**: The conjunction "when" correctly introduces a time clause indicating when the inhabitants were cooking.
3. **were**: The past tense verb "were" matches the past tense narrative of the passage.
4. **to use**: The infinitive "to use" is correctly used after "impossible" to indicate what was impossible.
5. **of**: The preposition "of" correctly indicates that over ninety percent of the damage was caused by fire.
6. **than**: The conjunction "than" correctly sets up the comparison between fire damage and damage from building collapse.