<span>It can be used by scientists everywhere its important to have the International System of Units.</span>
The third equation is properly balanced.
To figure this out, set up tables to check if each element has the same amount on both sides. If you do this for the third equation, copper, hydrogen, oxygen, and nitrogen are all balanced,
The first equation is incorrect due to the fact Iron, Fe, is not balanced on both sides. This is shown by the subscripts given.
The second equation is incorrect as Sulfur is not properly balanced and neither is sodium.
The fourth equation is incorrect as Aluminum is not properly balanced. On the reactants side, Aluminum is 4 while on the products, Aluminum is 8.
Hope this helps!
<span>The element that is used in light bulbs as a filament is tungsten - this is almost always the case in halogen and incandescent bulbs. Tungsten is chosen for this purpose because of the fact it can withstand temperatures of up to 4,500 degrees, as well as being incredibly flexible.</span>
It seems that you have missed the necessary details for us to answer this question, so I had to look for it. Anyway, here is the answer. If the US <span>adopted and maintained a policy of minimal control of co2 emissions, the level that we would expect its emissions to be in 2020 is that WE CAN'T TELL FROM THIS DATA. Hope this helps.</span>