C2H6 + 4o2 → 2CO2 + 3H2O...
Answer:
Question is incomplete i have added full question with explanation and reaction see attachment.
Answer:
I believe the answer is 7
Hag Fish and Lamprey
Vertebrates are the organism which posses a vertibral column(aka the spine or back bone structure), while the earliest had a head they lacked a spine and jaw, these jawless vertebrae lived 500-600 million years ago. they are the ancestors of bony fish which in time became amphibians and other groups of animals