Prepositions

Hi can you check these?

1- Taxes are imposed......... the people of a country to generate finances for various purposes. / I said = ON

2- Too much coffee isn't good for an insomniac or anyone having trouble with sleeping........ occasion. / I said = ON

3- You must keep your mind occupied........ nice thoughts if you want to deal with anxiety. / I said = WITH

4- Chipmunks are small rodents native....... the continents of North America and Asia. / I said = TO

Thanks.