Answer:
More than 40 percent measured above 5 ppb of lead, which the researchers considered an indication of a “very serious” problem.
<span>The concentration of pb2+ = 1.00mg/ml
Diluted Solution is 6.0 x 102 ml = 612 ml
Volume of the concentration of pb2+ is 0.054 mg/l is v
(vL)(1.00mg/ml) = (.612L)(0.054mg/l)
Volume = 0.033048L
Volume of the concentration of pb2+ is 0.054 mg/l = 33.048 ml.</span>
Answer:
The balanced chemical equation :

Explanation:
When calcium hydroxide reacts with hydrochloric acid it gives calcium chloride and water as a products. The chemical equation is given as:

According to question, solid calcium hydroxde is added to 38.0 mL of 0.410 M of HCl solution, so the chemical equation can be written as:

According to stoichiometry, when 1 mole of solid calcium hydroxide reacts with 1 mole of hydrochloric acid to gives 1 mole of aqueous calcium chloride and 1 mole of water.
We’re going to use the mass percent formula shown below:
For the percent by mass N, we’re going to rewrite the equation as:
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Problem Details
Calculate the mass percent composition of nitrogen in each nitrogen-containing compound:
c. NO2
<span>Scientific notation is used to express large numbers in a way that is to use, readable, comparable to other numbers and convenient. It is especially useful for things that are very large and very small because it is very tedious to work with many zero's when completing complex math problems.</span>