What is the legal limit?
The lowest concentration that can officially be reported for any constituent in drinking water is known as the "Legal Limit".
Contamination of water:
The level that safeguards human health and that water systems can attain with the finest technology is reflected in the regulatory limit for a contaminant.
<u><em>How does it occur:</em></u>
- Plumbing components are the main way that lead and copper enters the drinking water. The health effects of lead and copper exposure can range from brain damage to stomach discomfort.
- Nitrogen, bleach, salts, pesticides, metals, bacterial toxins, and human or animal medications are examples of chemical pollutants. Organisms in the water are biological pollutants. Other names for them include microorganisms and microbiological pollutants.
In order to control corrosion, the system must take a variety of additional measures if lead concentrations reach an action threshold of 15 ppb or copper concentrations exceed an action level of 1.3 ppm in more than 10% of measured customer taps.
Learn more about the contamination of water here,
brainly.com/question/7910855
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Answer : The concentration of 
ion, pH and pOH of solution is, 
, 1.05 and 12.95 respectively.
Explanation : Given,
Concentration of 
ion = 0.090 M
pH : It is defined as the negative logarithm of hydrogen ion or hydronium ion concentration.
The expression used for pH is:
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
First we have to calculate the pH.
The pH of the solution is, 1.05
Now we have to calculate the pOH.
The pOH of the solution is, 12.95
Now we have to calculate the concentration.
![pOH=-\log [OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5BOH%5E-%5D)
![12.95=-\log [OH^-]](https://tex.z-dn.net/?f=12.95%3D-%5Clog%20%5BOH%5E-%5D)
![[OH^-]=1.12\times 10^{-13}M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D1.12%5Ctimes%2010%5E%7B-13%7DM)
The concentration is,
C2H6O + 3O2 —> 2CO2 + 3H2O
The colour of copper sulphate solution is blue
Time taken for star to reach Earth = 7.5 years
<h3>Further explanation</h3>
Given
7.5 light years(distance Earth-star)
Required
Time taken
Solution
Speed of light=v = 3 x 10⁸ m/s
1 light years = 9.461 × 10¹⁵ m= distance(d)
So time taken for 1 light years :
time(t) = distance(d) : speed(v)
t = 9.461 × 10¹⁵ m : 3 x 10⁸ m/s
t = 3.154 x 10⁷ s = 1 years
So for 7.5 light years, time taken = 7.5 years
