Answer:
I think it mught be 12.9?
I think the correct answer from the choices listed above is option 2. When the products of a reaction are hotter than the reactants the reaction is endothermic. The change in temperature is a measure of energy difference of the states. Since energy must be conserved, so there must be a source of energy for the system.
Answer: Diatomic elements are pure elements that form molecules consisting of two atoms bonded together.
There are seven diatomic elements: hydrogen, nitrogen, oxygen, fluorine, chlorine, iodine, bromine.
Explanation:
Finding percent composition is fairly easy. You only need to divide the mass of an element by the total mass of the compound. We can do this one element at a time.
First, let's find the total mass by using the masses of the elements given on the periodic table.
7 x 12.011 (mass of Carbon) = 84.077
5 x 1.008 (mass of Hydrogen) = 5.04
3 x 14.007 (mass of Nitrogen) = 42.021
6 x 15.999 (mass of Oxygen) = 95.994
Add all of those pieces together.
84.077 + 5.04 + 42.021 + 95.994 = 227.132 g/mol is your total. Since we also just found the mass of each individual element, the next step will be very easy.
Carbon: 84.077 / 227.132 = 0.37016 ≈ 37.01 %
Hydrogen: 5.04 / 227.132 = 0.022189 ≈ 2.22 %
Nitrogen: 42.021 / 227.132 = 0.185 ≈ 18.5 %
Oxygen: 95.994 / 227.132 = 0.42263 ≈ 42.26 %
You can check your work by making sure they add up to 100%. The ones I just found add up to 99.99, which is close enough. A small difference (no more than 0.03 in my experience) is just a matter of where you rounded your numbers.
It is s<span>hutting down factories that discharge materials to rivers, </span>I am certain of it, because factors dump their waste in our waters, because they are a US Companies, and don't have the right to dump into international waters. Come on don't you remember any of that, companies dumping in our waters etc.