Answer:
An acid is a substance that donates hydrogen ions. ... Now there are more hydrogen ions than hydroxide ions in the solution. This kind of solution is acidic
 
        
             
        
        
        
Era is used to mark the boundaries of geological time scale by using radio carbon dating technique.
Explanation:
Geological time starts with Precambrian time.
Geologically, time is divided between the Precambrian era and present time into era.
The three eras are Paleozoic era, Triassic period and Cenozoic era.
Era is further divided into periods.
Scientists use radio carbon dating to study fossils and rock formation. With this study they were able to divide them in exact geological scale.
Geologic scale is the record of events in earth's history and evolution.
 
        
             
        
        
        
Force is mass × acceleration and it is measured in Newtons.
 Mass = 3kg
Acceleration = 9m/s²
F = ma
F = 3×9
F = 27Newtons.
        
             
        
        
        
Answer:
may be 
the discovery of new evidence 
Explanation:
Accepted theories may be modified or overturned as new evidence and perspective emerges. Scientists are likely to accept a new or modified theory if it explains everything the old theory did and more. The process of theory change may take time and involve controversy, but eventually the scientific explanation that is more accurate will be accepted.
 
        
             
        
        
        
Species you can remember it by Dear King Philip Came Over For Great Spaghetti. domain, kingdom, phylum, class, order, family, genus, species.