What is the target heart rate for a 24 year old?
2 answers:
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Answer : The number of molecules of A needed to make 5000 molecules of AB will be, 5000
Explanation :
Law of conservation of mass : It states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
The given balanced chemical reaction is,
As per question, molecule B is an excess reagent because it had enough molecule to make 5000 molecules of AB. So, molecule A is limiting reagent.
From the balanced reaction, we conclude that
As, 1 molecule of AB produced from 1 molecule of A
So, 5000 molecule of AB produced from 5000 molecule of A
Hence, the number of molecules of A needed to make 5000 molecules of AB will be, 5000
Answer: Choice B
There are triple bonds between the carbon (C) and oxygen (O) atoms. Then there are 2 dots on either side
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Explanation:
When it comes to interaction and chemistry, all that matters is the valence shell or valence electrons. This is the outermost shell. This is because various elements do not interact with the inner electrons (they're locked in place so to speak and don't move to other elements).
Carbon has 6 protons, which is what uniquely makes up this element. This means there are 6 electrons. The inner shell has 2 electrons and the valence shell has 4 electrons. Two electrons are shown as the two blue dots on the left side of the C. The other two electrons form two of the lines, or the bonds, between the C and O.
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Oxygen has 8 protons and 8 electrons. It has 2 electrons in the inner shell and 6 electrons in the valence shell. Two of those electrons are the red dots on the right side of the O. The other 4 electrons are shared to form the bonds with the carbon atom.
This is where things get a bit tricky. I've shown a diagram below indicating that one of the oxygen electrons (red dot) is passed to the carbon, as this carbon atom is pulling on the oxygen electron. But the oxygen atom is pulling on it as well, which forms one of the triple bonds.
So this is why diagram B is the final answer. This is something you can logically determine (remembering the rules of how each electron shell is formed), or it's something you'll need to memorize. In the real world, it's easy to forget a lot of info like this, so that's why having it handy as a lookup reference is preferable.
