The energy that an object has is moving
On the off chance that one of the reactants is in overabundance yet you don't know which one it is, you have to compute the hypothetical item mass for the both reactants, with a similar item, and whichever has the lower yield is the one you use to precisely depict masses/sums for the condition, since you can't have more than the non-abundance reactant can create.
To determine the molar mass, you need to get the atomic mass of the molecule. To do this, check the periodic table for the atomic mass or average atomic weight of each element.
Mg = 24.305 x 1 = 24.305 amu
O = 15.9994 x 2 =31.9988 amu
H = 1.0079 x 2 = 2.0158 amu
Then, add all the components to get the atomic mass of the molecule.
24.305 amu + 31.9988 amu + 2.0158 amu = 58.3196 amu
The atomic mass is just equivalent to its molar mass.
So, the molar mass of Magnesium hydroxide (Mg(OH)2) is 58.3196 g/mol.
Answer:
0.56L
Explanation:
This question requires the Ideal Gas Law: 
where P is the pressure of the gas, V is the volume of the gas, n is the number of moles of the gas, R is the Ideal Gas constant, and T is the Temperature of the gas.
Since all of the answer choices are given in units of Liters, it will be convenient to use a value for R that contains "Liters" in its units:
Since the conditions are stated to be STP, we must remember that STP is Standard Temperature Pressure, which means 
and 
Lastly, we must calculate the number of moles of 
there are. Given 0.80g of , we will need to convert with the molar mass of . Noting that there are 2 oxygen atoms, we find the atomic mass of O from the periodic table (16g/mol) and multiply by 2: 
Thus, 
Isolating V in the Ideal Gas Law:
...substituting the known values, and simplifying...
So, 0.80g of would occupy 0.56L at STP.
I would say C is the most correct.
In D it depends on what water source you're using. Let's say it is a waterfall, then the source of the water (melting ice or a lake) may disappear in the future.
If you're using underwater "windmills" placed in the ocean, then you would expect it to last a while as the ocean will not disappear in the near future.
