Answer: A=12
Explanation:
4.5
The amount of chemical remaining after twelve seconds in the first reaction is:
A = 12 - 0.5(12)
= 12 - (6)
= 6
In the dissolved reaction, the amount of chemical loses half of itself every four seconds. This is the same thing as dividing by 2 every four seconds.
This is an exponential decay, so the amount of chemical divides by 4 every eight seconds, and by 8 seconds every twelve seconds. The amount remaining after twelve seconds in the second reaction is:
A' = 12/8
= 3/2
= 1.5
The difference between the amounts of chemical remaining is:
6 - 1.5 = 4.5
Therefore, A is 4.5 g greater than A' after twelve seconds.
 
        
             
        
        
        
Answer:
there are 1/4 cups of Super Grain Cereal in the mixture
Explanation:
Super Grain cereal provides 240 calories per cup. Thus, for s cups of Super Grain cereal, there will be 240s calories
Crunchy Grain cereal provides 210 calories per 3/4 cups. Thus, 210 ÷ 3/4 per cup.
210 ÷ 3/4 = 280 calories, For c cups of Crunchy Grain cereal, there will be 280c calories
Jennifer mixes c cups of Crunchy Grain cereal, having 280 calories and s cups of Super Grain cereal, having 240 calories to get a final 1 cup mixture containing 270 calories, which can be expressed mathematically as:
280c + 240s = 270 ------- eqn(1)
Since, s cups of Super Grain cereal and c cups of Crunchy Grain cereal equals 1 cup, of the final mixture 
c + s = 1 ------- eqn(2)
from eqn(2), 
c = 1 - s
substitute c = 1 - s into eqn(1)
280(1 - s) + 240s = 270
280 - 280s + 240s = 270
- 40s = 270 - 280
-40s = -10
s = (-10)/(-40)
s = 1/4
Therefore, there are 1/4 cups of Super Grain Cereal in the mixture
Ans B
(Hope this helps can I pls have brainlist (crown)☺️)
 
        
             
        
        
        
The entropy change ΔS for the combustion of methane to carbon dioxide and liquid water is -242.6 J/mol.K
<h3>What is the Entropy in a Chemical system?</h3>
In a chemical system, Entropy (ΔS) is a quantitative measure of the variety of possible ways to disperse energy inside a chemical system.
- In an isothermal process, entropy is determined as the quantity of heat transmitted to a system.
The chemical reaction for the combustion of methane can be expressed as:

The standard entropy of the combustion is expressed as:

Replacing the standard entropies of the compounds into the above equation, we have:


Learn more about entropy here:
brainly.com/question/6364271