How Can You Tackle Environmental Chemistry Questions Effectively?

[Priscilla]

Attachments: Questions and Answers

I try my very best to do the questions. But I really don't know how to get to the answer.
Could someone give me some hints of the questions: what assumption should I make if information is not given, and what equation can I use?

 

[Bystander]

The questions look to be complete (no assumptions necessary). The thumbnails are not legible --- rescan, type 'em, outline the steps you took --- something.

 

[Priscilla]

I resized them.

 

[Priscilla]

Second part