The pH unit has 10x as many hydrogens ions as the unit above.
Ex: A pH of 5 would have 10x more hydrogen ions than a pH of 6 
and 100x more than if it had a pH of 7.
With a pH of 9 and 3, this is equivalent to 10⁶
So your answer should be:
1,000,000
        
             
        
        
        
Answer:
Chemical Change
Explanation:
Physical change normally mean that the change can revert back to its orginal state, which in this case that is not possible therfore it is a chemical change. 
 
        
             
        
        
        
B. Mn + NiBr₂  →  Ni + MnBr₂
Explanation:
The reaction that can be predicted of all is Mn + NiBr₂  →  Ni + MnBr₂.
The activity series is used to predict the products of single displacement reactions. 
The series ranks metals in order of their reactivity. Those higher up in the series are highly reactive metals. Those at the bottom are slightly to non-reactive metals. 
 For a single displacement reaction to occur, a metal higher up in the activity series displaces one that is lower in the series. 
   Reaction A will not occur, Ba is higher in the series
   Reaction C will not occur, Pt and Au are unreactive
   Reaction D will not occur as Zn is lower in the series
Mn is higher in the reactivity series and it will displace Ni from the solution. 
Learn more: 
Synthesis reaction brainly.com/question/4216541
#learnwithBrainly
 
        
             
        
        
        
Vanillin is the common name for 4-hydroxy-3-methoxy-benzaldehyde.
See attached figure for the structure.
Vanillin have 3 functional groups:
1) aldehyde group:  R-HC=O, in which the carbon is double bonded to oxygen
2) phenolic hydroxide group: R-OH, were the hydroxyl group is bounded to a carbon from the benzene ring
3) ether group: R-O-R, were hydrogen is bounded through sigma bonds to carbons
Now for the hybridization we have:
The carbon atoms involved in the benzene ring and the red carbon atom (from the aldehyde group) have a <u>sp²</u> hybridization because they are involved in double bonds.
The carbon atom from the methoxy group (R-O-CH₃) and the blue oxygen's have a  <u>sp³</u>  hybridization because they are involved only in single bonds.