Here are the corrections for the mistakes in each sentence:

1. Walt Disney Studios, a famous **film studio**, has produced hundreds of cartoons for children.
2. A number of cleaning products **contain** harmful chemicals, causing some kinds of disease.
3. If the factory continues **to dump** poison into the lake, all the fish and other aquatic animals would die.
4. The thinning of the ozone layer is caused by smoke in the air from factories, vehicles, and **industry**.
5. Your item was sent last Friday, and it should **be delivered** to you on Sunday at the latest.
6. Of the near 1,900 volcanoes active today, about ninety percent can be found within the ring of fire.
7. I sometimes take John's coat **instead of** mine because the two of them look the same.
8. Many people think that planting more trees is a good way to protect our planet.