If pH is less than seven (pH<7), solution is acidic.
If pH is equal seven (pH = 7), solution is neutral.
If pH is greater than seven (pH > 7), solution is basic.
Some examples:
1) Acidic - gastric juices pH 1, lemon juice pH 2.2, tomato juice pH 4.
2) Neutral - salt solution pH 7.
3) Alkaline - baking soda pH 9, bleach pH 13.
pH is a numeric scale used to specify the acidity or basicity of an aqueous solution.
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Answer : The time taken by the reaction is 
Explanation :
The expression used for second order kinetics is:
![kt=\frac{1}{[A_t]}-\frac{1}{[A_o]}](https://tex.z-dn.net/?f=kt%3D%5Cfrac%7B1%7D%7B%5BA_t%5D%7D-%5Cfrac%7B1%7D%7B%5BA_o%5D%7D)
where,
k = rate constant = 
t = time = ?
= final concentration = 0.40 M
= initial concentration = 2.16 M
Now put all the given values in the above expression, we get:


Therefore, the time taken by the reaction is 
The answer is A because the information is stating that when one chemical combined with another chemical, it had new properties which is essentially answer choice A
Explanation:
D air.......,..........,.......