Answer:
40/220 ×100=18.6 is all I got I know that by heart so um yea
Explanation:
Answer:
Probably A.
Explanation:
Its either A or C. A is more probable imo
Answer:
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Explanation:
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Answer:
![\boxed {\boxed {\sf About \ 1.5 * 10^{24} \ atoms \ Si}}](https://tex.z-dn.net/?f=%5Cboxed%20%7B%5Cboxed%20%7B%5Csf%20About%20%5C%201.5%20%2A%2010%5E%7B24%7D%20%5C%20atoms%20%5C%20Si%7D%7D)
Explanation:
When converting from moles to atoms, we must use Avogadro's number. This number tells us there are 6.022 * 10²³ atoms in 1 mole. We can multiply this number by the number of moles.
First, we must set up Avogadro's number as a ratio.
![\frac {6.022 \ * 10^{23} \ atoms \ Si }{1 \ mol \ Si}}](https://tex.z-dn.net/?f=%5Cfrac%20%7B6.022%20%5C%20%2A%2010%5E%7B23%7D%20%5C%20atoms%20%5C%20Si%20%7D%7B1%20%5C%20mol%20%5C%20Si%7D%7D)
Next, multiply the number of moles by the ratio.
![2.5 \ mol \ Si *\frac {6.022 \ * 10^{23} \ atoms \ Si }{1 \ mol \ Si}}](https://tex.z-dn.net/?f=2.5%20%5C%20mol%20%5C%20Si%20%2A%5Cfrac%20%7B6.022%20%5C%20%2A%2010%5E%7B23%7D%20%5C%20atoms%20%5C%20Si%20%7D%7B1%20%5C%20mol%20%5C%20Si%7D%7D)
When we multiply, the moles of silicon will cancel.
![2.5 * \frac {6.022 \ * 10^{23} \ atoms \ Si }{1}}](https://tex.z-dn.net/?f=2.5%20%2A%20%5Cfrac%20%7B6.022%20%5C%20%2A%2010%5E%7B23%7D%20%5C%20atoms%20%5C%20Si%20%7D%7B1%7D%7D)
Since the denominator of the fraction is 1, we can cancel it out too.
![2.5 * {6.022 \ * 10^{23} \ atoms \ Si }](https://tex.z-dn.net/?f=2.5%20%2A%20%20%7B6.022%20%5C%20%2A%2010%5E%7B23%7D%20%5C%20atoms%20%5C%20Si%20%7D)
![1.5055 * 10^{24} \ atoms \ Si](https://tex.z-dn.net/?f=1.5055%20%2A%2010%5E%7B24%7D%20%5C%20atoms%20%5C%20Si)
The original measurement (2.5 moles) has 2 significant figures (2 and 5). Therefore we must round to 2 sig figs. For this question, 2 sig figs is the tenth place.
The 0 in the hundredth place tells us to leave the 5 in the tenth place.
![1.5 * 10^{24} \ atoms \ Si](https://tex.z-dn.net/?f=1.5%20%2A%2010%5E%7B24%7D%20%5C%20atoms%20%5C%20Si)
There are about <u>1.5 * 10²⁴ atoms of silicon.</u>
Change of matter
- Know simple science rules and that will help.