A chemical change produces a new substances. Examples of chemical changes are burning a cooking egg
Answer:

Explanation:
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In this case, according to the given combustion reaction of octane, it is possible for us to perform the stoichiometric method in order to calculate the mass of octane that is required to consume 300.0 g of oxygen by considering the 2:25 mole ratio, and the molar masses of 114.22 g/mol and 32.00 g/mol respectively:

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I believe the major periodic trends include; electronegativity, ionization energy, electron affinity, atomic radius, melting point, and the metallic character. Periodic trends, arising from the arrangement of the periodic table, provide chemists with an invaluable tool to quickly predict an element's property.
6.52 × 10⁴ L. (3 sig. fig.)
<h3>Explanation</h3>
Helium is a noble gas. The interaction between two helium molecules is rather weak, which makes the gas rather "ideal."
Consider the ideal gas law:
,
where
is the pressure of the gas,
is the volume of the gas,
is the number of gas particles in the gas,
is the ideal gas constant, and
is the absolute temperature of the gas in degrees Kelvins.
The question is asking for the final volume
of the gas. Rearrange the ideal gas equation for volume:
.
Both the temperature of the gas,
, and the pressure on the gas changed in this process. To find the new volume of the gas, change one variable at a time.
Start with the absolute temperature of the gas:
,
.
The volume of the gas is proportional to its temperature if both
and
stay constant.
won't change unless the balloon leaks, and- consider
to be constant, for calculations that include
.
.
Now, keep the temperature at
and change the pressure on the gas:
,
.
The volume of the gas is proportional to the reciprocal of its absolute temperature
if both
and
stays constant. In other words,
(3 sig. fig. as in the question.).
See if you get the same result if you hold
constant, change
, and then move on to change
.