Answer:
They expressed it as rate of change in concentration of reactants or products in a chemical reaction
 
        
                    
             
        
        
        
Answer:
The play will be more  appealing to a younger audience. 
Explanation:
A younger audience will more likely appreciate current pop hits rather than classical score.
 
        
                    
             
        
        
        
Answer:
D. The electrochemical reaction of the battery must be reversible.
Explanation:
The batteries are based on the production of an electric flux given by a<u> redox reaction</u>. This reaction is <u>spontaneous</u> and is<u> thermodynamically favored</u>. 
Thus, when the reactants to the reaction are finished, the flow of current stops and ends. Therefore, when current is administered from another source, the reaction <u>changes its direction</u> and reagents that were previously consumed begin to occur. Therefore the condition for it to be <u>rechargeable</u> is that the reaction can go <u>forward or backward</u>, that is, it is <u>reversible</u>.
 
        
             
        
        
        
Answer:
a. Change of state
Explanation:
Because you will see that the state has changed
 
        
             
        
        
        
Answer:
Cost to supply enough vanillin is 
Explanation:
Threshold limit of vanillin in air is  per litre means there should be
 per litre means there should be  of vanillin in 1L of air to detect aroma of vanillin.
 of vanillin in 1L of air to detect aroma of vanillin.

So, 
So amount of vanillin should be present to detect = 
As cost of 50 g vanillin is  therefore cost of
 therefore cost of   vanillin =
vanillin = 