How many grams are in 4.5 x 10^24 atoms of carbon

Yes it would be a physical change.

Isec i will do it and them i will let you know

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.