Compounds have different conductivity because if they have the same meaning it wont be a other word. the compounds have to have a conductivity so there can be more meanings.
        
             
        
        
        
Hi!
I think the oxidation state of all the atoms should change. :) 
Hope this helps
        
             
        
        
        
Answer:
C.  Butanal , is the aldehyde 
Explanation:
A . It is carboxylic acid : ---COOH group
B. It is Ester : ----COOR group , Here R = CH3
C. It is Aldehyde : -----CHO group
D. It is ketone : ----C=O group
See image :
 
        
             
        
        
        
<u>Answer:</u>
<em>Silver tarnishing as the silver metal reacts with sulphur is a chemical change.</em>
<u>Explanation:</u>
Tarnishing is the process of chemical change occurring on the surface of objects leading to corrosion or other defects on the surface. The remaining options like dilution, eroding is a physical change where the concentration of salt and rock particles will be decreased, respectively. 
Similarly for soil drying also the concentration of water will be decreased leading to a physical change from wetty or dry soil. 
But the last option which indicates tarnishing of silver metal on reaction with sulphur is a chemical process as the surface of silver metal will be reacting to sulphur and leads to lose of electrons which leads to corrosion of the surface or tarnishing of silver.