If you have 12 atoms of hydrogen before a chemical reaction, the number of hydrogen atoms that will be present after the chemical reaction is 12 atoms.
The Law of Conservation of Mass (LOCOM) states that mass is neither created nor destroyed before and after any chemical reaction.
According to the Law of Conservation of Mass (LOCOM), a balanced chemical equation requires that the number of atoms on the reactant side must be equal to the number of atoms on the product side of any chemical reaction.
In this context, a chemical reaction having 12 atoms of hydrogen as reactants at the beginning, should also produce a total of 12 atoms of hydrogen as products at the end of the chemical reaction.
Answer:

Explanation:
The process during which pressure remains constant is called an isobaric process.
Surface air pressure is a consequence of the weight of the air acting on its surface. For example, if you are standing on Mars, the pressure around you is what you call the surface air pressure. Thus, that surface air pressure must be 0.007 atm.
The trickiest part of this problem was making sure where the Yakima Valley is.
OK so it's generally around the city of the same name in Washington State.
Just for a place to work with, I picked the Yakima Valley Junior College, at the
corner of W Nob Hill Blvd and S16th Ave in Yakima. The latitude in the middle
of that intersection is 46.585° North. <u>That's</u> the number we need.
Here's how I would do it:
-- The altitude of the due-south point on the celestial equator is always
(90° - latitude), no matter what the date or time of day.
-- The highest above the celestial equator that the ecliptic ever gets
is about 23.5°.
-- The mean inclination of the moon's orbit to the ecliptic is 5.14°, so
that's the highest above the ecliptic that the moon can ever appear
in the sky.
This sets the limit of the highest in the sky that the moon can ever appear.
90° - 46.585° + 23.5° + 5.14° = 72.1° above the horizon .
That doesn't happen regularly. It would depend on everything coming
together at the same time ... the moon happens to be at the point in its
orbit that's 5.14° above ==> (the point on the ecliptic that's 23.5° above
the celestial equator).
Depending on the time of year, that can be any time of the day or night.
The most striking combination is at midnight, within a day or two of the
Winter solstice, when the moon happens to be full.
In general, the Full Moon closest to the Winter solstice is going to be
the moon highest in the sky. Then it's going to be somewhere near
67° above the horizon at midnight.
The correct answer is:
<span>C) The actual frequency of the siren does not change despite appearances.
In fact, Bob will observe an increase in the apparent frequency as the emergency vehicle approaches him, while Jill will observe a decrease in the apparent frequency as the emergency vehicle moves away from him, because of the Doppler effect (the relative velocity between the observer and the source of the sound is changing), but this effect involves the apparent frequency, while the real frequency of the siren will remain the same.</span>