Chlorine is a halogen and all halogens and oxygen, nitrogen and hydrogen are diatomics
        
                    
             
        
        
        
Always use least amount of sig figs possible. So this 9.7 would be (answer): 2 sig figs
        
             
        
        
        
Answer:
The correct answer is - c. adding 10 mL bleach to 90 mL water.
Explanation:
To prepare a effective disinfecting solution to clean the countertops is a bleasce solution of 10% solution of bleach. The ten percent of the bleach solution means there are one volve of bleach and 9 volume of clean water in this solution. 
So, preparing the 1/10 or ten percent solution is where adding 10 ml of bleach which is diluted to 90 ml clean water. This diluted solution can be use as disinfecting solution.