The selective loss of unused connections among brain cells is called

Pruning

Explanation:

Pruning or synaptic pruning is brain's way of clearing unnecessary signals that are no longer needed. It mostly occur in childhood and adolescence because brain want to get faster by avoiding unused impulses in Synapses. Synapse is the space between neurons through which signals are being transferred.

Pruning of brain cells.

Explanation:

Basically, pruning is the removing of unwanted branches from a tree or in this case unwanted or unused connection removal among brain cells to increase their activity and speed.

Pruning of brain cells usually occurs in childhood and adolescence by removing of the unnecessary signals to increase the brain activity.

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

multiplying and dividing the two decimals and the eqations by the same number of the overalls