Answer:
In 1935
First synthetic fiber produced by man
Got it's name from Cities of New York And London
0.000001ppm
Explanation:
Mass of fluoride = 500g
Volume of water = 500000liters
Unknown:
Parts per million of fluoride = ?
Solution:
The parts per million is the amount of solute in milligram dissolved in a liter of water or milligram per kilogram of solvent
It is a unit used to express very small concentration.
we need to convert g - mg
500g = 500 x 10⁻³mg = 0.5mg
Concentration in parts per million = 
Concentration in parts per million =
= 0.000001ppm
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Data:
weight of water before heating = 0.349
weight of hydrate before heateing = 2.107
Formula:
Weight percent of water = [ (weight of water) / (weight of the hydrate) ] * 100
Solution:
Weight percent of water = [ 0.349 / 2.107] * 100 ≈ 16.6 %
Answer: 16.6%
<u>Answer</u>:-
Name of element = Lead
Symbol ♾ of Lead = Pb
Atomic no. = 82
Atomic mass = 207.2 amu
No. of protons = 82
No. of electrons = 82
Yes, lead(Pb) is a metallic element and certainly it has 6 electron shells which means 6 energy level.
If you find anything unclear you can ask me...