The collection of which of the following gases involves a catalyst? A)oxygen
B)ammonia
C)carbon dioxide

Answer two atoms of oxygen;

We can't until we know what we are working with or on

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.