x = 20 long tables
y = 5 round table
Explanation:
We have the following system of equations:
x + y = 25
8x + 6y = 190
From the first equation we have:
x = 25 - y
And we replace x in the second equation:
8(25 - y) + 6y = 190
200 - 8y + 6y = 190
200 - 2y = 190
200 - 190 = 2y
10 = 2y
y = 5
Now we insert the value of y in the next equation:
x = 25 - y
x = 25 - 5
x = 20
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The other dude is rude wrong
The correct answer is Dmitri Mendeleev
Answer:
Natural gas combustion equation:
CH4 + O2 ==> CO2 + 2 H2O + HEAT
Octane or oil combustion equation:
2C8H18 + 25 O2 ===> 16CO2 + 18 H2O.
If these fuels were replaced by self-sustaining energy sources, the contamination of the environment would be less, since their combustion generates toxic compounds that damage the ozone layer, promoting the greenhouse effect, increasing the Earth's temperature and also promoting the increase in the passage of ultraviolet radiation.
Explanation:
The combustion reactions are exothermic, and irreversible, they can be complete and incomplete combustions.
They always consist of oxygen as a reagent and water and carbon dioxide as a product (complete), in the case of the incomplete the difference is that the products vary and there may be waste or chemical compounds that failed to burn.
As long as the equation in question can be expressed as the sum of the three equations with known enthalpy change, its 
can be determined with the Hess's Law. The key is to find the appropriate coefficient for each of the given equations.
Let the three equations with given be denoted as (1), (2), (3), and the last equation (4). Let 
, 
, and 
be letters such that 
. This relationship shall hold for all chemicals involved.
There are three unknowns; it would thus take at least three equations to find their values. Species present on both sides of the equation would cancel out. Thus, let coefficients on the reactant side be positive and those on the product side be negative, such that duplicates would cancel out arithmetically. For instance, 
shall resemble the number of 
left on the product side when the second equation is directly added to the third. Similarly
Thus
and
Verify this conclusion against a fourth species involved- 
for instance. Nitrogen isn't present in the net equation. The sum of its coefficient shall, therefore, be zero.
Apply the Hess's Law based on the coefficients to find the enthalpy change of the last equation.
The answers would be:
In a solution, the solvent is present in a greater amount.
In a solutions, the solute dissolves in a solvent.
In general, these are the best answers. The solute is what is being dissolved and the solvent is what dissolves. A solvent comes in greater amounts in a solution and it is the dissolving agent.
For example, sugar and water.
To make a sugar water solution, you will need to dissolve sugar in water. Sugar is the solute in this case because it is what is being dissolved. The water is the solvent, because it dissolves the sugar.
If you had more sugar than water, then you cannot make a solution.
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