Environmental Chemistry studies the health hazards associated with lead, which is dangerous to humans.
Environmental Chemistry studies chemicals present in air, water and soil and their impact on humans and their environment.
Now, it was discovered that even low doses of lead particles in the paint when inhaled or ingested caused damaging effect to the body such as Impaired balance, seizures, ataxia and even death.
With the role of Environmental chemists in thier research and findings, the world has been informed on the negative effect on the expose of lead and other heavy metals like it to man and his environment.
See more here:brainly.com/question/22517940
Explanation:tr
a) Molar mass of HF = 20 g/mol
Atomic mass of hydrogen = 1 g/mol
Atomic mass of fluorine = 19 g/mol
Percentage of an element in a compound:
Percentage of fluorine:
Percentage of hydrogen:
b) Mass of hydrogen in 50 grams of HF sample.
Moles of HF = 
1 mole of HF has 1 mole of hydrogen atom.
Then 2.5 moles of HF will have:
of hydrogen atom.
Mass of 2.5 moles of hydrogen atom:
1 g/mol × 2.5 mol = 2.5 g
2.5 grams of hydrogen would be present in a 50 g sample of this compound.
c) As we solved in part (a) that HF molecules has 5% of hydrogen by mass.
Then mass of hydrogen in 50 grams of HF compound we will have :
5% of 50 grams of HF = 
Answer:
you sound like a cool guy, ill email ya one of these days
Explanation:
Im pretty positive its A , hope this helps!
d = diameter of the seat = 12 inch
we know that , 1 inch = 0.0254 m
hence
d = diameter of the seat = 12 inch = 12 (0.0254) m = 0.305 m
r = radius of seat = diameter/2 = d/2 = 0.305/2 = 0.1525 m
A = area of seat = πr²
m = mass of the person = 65 kg
g = acceleration due to gravity = 9.8 m/s²
F = force due to weight of person on the seat = mg
pressure on the seat is given as
P = F/A
P = mg/A
P = mg/(πr² )
inserting the values
P = (65 x 9.8)/((3.14) (0.1525)²)
P = 8723.1 N/m²
