1) How many molecules is 8.45 moles of ammonia, NH3?

I’m not sure what your trying to say here.. can you clarify again?

It's called the falling actionwrong subject by the way

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.