Answer:
8.4 dollars
Step-by-step explanation:
The error is in the resolution of the proportion. In fact, the initial proportion is correct:

where x is the total cost. However, the following step of the resolution is wrong. In fact, the correct resolution is the following:
- Multiplying by x on both sides:

- Multiplying by 3.5 no both sides:

And now we can find x:

So, the total cost is 8.4 dollars.
The number of mole of pure 11C (carbon-11) initially present is 0.2727 mole
<h3>Description of mole </h3>
The mole of a substance is related to it's mass and molar mass according to the following equation
Mole = mass / molar mass
With the above formula, we can obtain the number of mole of pure 11C. Detail below:
<h3>How to determine the mole of 11C</h3>
From the question given, the following data were obtained:
- Molar mass of 11C = 11 g/mol
- Mass of 11C = 3 g
- Mole of 11C =?
Mole = mass / molar mass
Mole = 3 / 11
Mole = 0.2727 mole
Therefore, the number of mole of pure 11C initially present is 0.2727 mole
Learn more about mole:
brainly.com/question/13314627
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Answer:
the expression equal to this is 20 X /25 is the answer for the expression is 4 x/ 5
Step-by-step explanation:
Answer:
A is the correct one i guess... hope it helps uh