Answer:

Explanation:
We have to combine the following formula to find the mass yield:


The diffusion coefficient : 
The area : 
Time : 
ΔC: 
Δx: 
Now substitute the values

![M=-(6.0*10^{-8} m/s^{2})(0.25 m^{2})(3600 s/h)[(0.64-3.0kg/m^{3})(3.1*10^{-3}m)]](https://tex.z-dn.net/?f=M%3D-%286.0%2A10%5E%7B-8%7D%20m%2Fs%5E%7B2%7D%29%280.25%20m%5E%7B2%7D%29%283600%20s%2Fh%29%5B%280.64-3.0kg%2Fm%5E%7B3%7D%29%283.1%2A10%5E%7B-3%7Dm%29%5D)

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Answer:
Engineering is the use of science and math to design or make things. People who do engineering are called engineers. They learn engineering at a college or university. Engineers usually design or build things. Some engineers also use their skills to solve technical problems.
Explanation:
Many of the substances in welding smoke, such as chromium, nickel, arsenic, asbestos, manganese, silica, beryllium, cadmium, nitrogen oxides, phosgene, acrolein, fluorine compounds, carbon monoxide, cobalt, copper, lead, ozone, selenium, and zinc, can be extremely toxic.