Compare and contrast the reaction between 1) halogens and alkanes and between 2) halogens and alkenes. 1) Occurs ; requires i by 2) Occurs ​

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.

Aquantity of that isotope to decay to 1/2 of  its original value

Ithink b not to sure hope that : )