Answer: 
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.
The balanced chemical equation is:
<u> </u> The pH of 0.035 M aqueous aspirin is 2.48
<u>Explanation:</u>
We are given:
Concentration of aspirin = 0.035 M
The chemical equation for the dissociation of aspirin (acetylsalicylic acid) follows:

<u>Initial:</u> 0.035
<u>At eqllm:</u> 0.035-x x x
The expression of
for above equation follows:
![K_a=\frac{[C_9H_7O_4^-][H^+]}{[HC_9H_7O_4]}](https://tex.z-dn.net/?f=K_a%3D%5Cfrac%7B%5BC_9H_7O_4%5E-%5D%5BH%5E%2B%5D%7D%7B%5BHC_9H_7O_4%5D%7D)
We are given:

Putting values in above expression, we get:

Neglecting the value of x = -0.0037 because concentration cannot be negative
So, concentration of
= x = 0.0033 M
- To calculate the pH of the solution, we use the equation:
![pH=-\log[H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%5BH%5E%2B%5D)
We are given:
= 0.0033 M
Putting values in above equation, we get:

Hence, the pH of 0.035 M aqueous aspirin is 2.48
Answer:
Element.
Explanation:
Aluminum is an element because it is not separable into simpler substances. One thing important to keep in mind is that if something is on the Periodic Table of Elements, it is 100% an element.
Answer:
In 4 years the carbon monoxide level reach 7.8 parts per million.
Explanation:
The average daily level of carbon monoxide in the air is given by :
parts per million..[1]
The population of the region after t years is modeled by the formula :
...[2]
If level of carbon monoxide level reach 7.8 parts per million in t years.
Using [1] to calculate value of x.
c(x)= 7.8 parts per million
c(x) = 0.5x + 2 parts per million
7.8 parts per million = (0.5x + 2 ) parts per million
Solving for x , we get ;
x = 11.6
Using [2] to calculate value of t.:
x(t) = 11.6

Solving for 't' we get ;
t = 4 years
In 4 years the carbon monoxide level reach 7.8 parts per million.