Answer:
the answer is O²- hopefully 
 
        
             
        
        
        
Answer:
He assumed wrongly
Explanation:
It happened this way because the person assumed wrongly. 
Most other compounds have the same physical appearance as water especially when in liquid form. 
- This can be a very tricky one in the laboratory. 
- The sense of taste is not the best way to fathom what a particular compound is made up of. 
- This is the reason why this student or person faced this sort of problem. 
- Water has different properties that can be tested for using simple techniques in the laboratory. 
 
        
             
        
        
        
See attachment file below.
Use formulas relating pka, ka, and ph
Hope it helped!