If an ecological pyramid showed these organisms, the level that would retain the most energy from the Sun is . The level that would retain the least energy from the Sun is
.

A pex Predator

Explanation:

When we look at the energy pyramid, we have:

0.01% - A pex Predator

0.1% - Tertiary Consumers

1% - Secondary Consumers

10% - Primary Consumers

100% - Primary Producers

So if we have the primary producers having 100% energy efficiency level from the sun, and primary consumers only get 10% by eating primary producers, etc., then a pex predators get the least; they only get 0.01% of the sun's energy.

*Sorry if the word a-pex isn't how it is supposed to be spelled. thinks it is a swearword

5 structural isomers

the isomers are:

n-exane :   ch3ch2ch2ch2ch2ch3

2-methylpentane :   ch3ch(ch3)ch2ch2ch3

3-methylpentane :   ch3ch2ch(ch3)ch2ch3

2,3-dimethylbutane :   (ch3)2chch(ch3)2

2,2-dimethylbutane :   (ch3)3cch2ch3