Question

name: mr. chino e
what is the correct number for 7.58 x 10^-10?
convert 4 hours per day to days per year.
convert 75 miles per hour to feet per second.
use the density chart for the next 4 problems:
100.0 grams of copper occupies how much space?
100.0 grams of oxygen occupies how much space?
i have an unknown substance that weighs 15.0 grams and displaces 1.67 ml when placed in water. what is the substance?
an experiment calls for 78.11 grams of magnesium. what is its volume?
draw the phase change triangle below!!!

Explanation:

Step1: Evaluate scientific - notation number

The number $7.58\times10^{- 10}=0.000000000758$.

Step2: Convert hours per day to days per year

There are 365 days in a year. If there are 4 hours per day, then the total number of hours per year is $4\times365 = 1460$ hours. To convert this to days, divide by 24 (since there are 24 hours in a day). So, $\frac{1460}{24}=\frac{365}{6}\approx60.83$ days per year.

Step3: Convert miles per hour to feet per second

1 mile = 5280 feet and 1 hour = 3600 seconds.
If the speed is 75 miles per hour, first convert miles to feet: $75\times5280$ feet per hour. Then convert hours to seconds. The speed in feet per second is $\frac{75\times5280}{3600}=110$ feet per second.

Step4: Find volume of copper

The density formula is $
ho=\frac{m}{V}$, where $
ho$ is density, $m$ is mass, and $V$ is volume. For copper, $
ho = 8.96\ g/cm^{3}$ and $m = 100.0\ g$. Rearranging the formula for $V$, we get $V=\frac{m}{
ho}=\frac{100.0}{8.96}\approx11.16\ cm^{3}$.

Step5: Find volume of oxygen

For oxygen, $
ho=0.00133\ g/cm^{3}$ and $m = 100.0\ g$. Using $V=\frac{m}{
ho}$, we have $V=\frac{100.0}{0.00133}\approx75187.97\ cm^{3}$.

Step6: Identify unknown substance

The density of the unknown substance is $
ho=\frac{m}{V}$, where $m = 15.0\ g$ and $V = 1.67\ mL=1.67\ cm^{3}$. So, $
ho=\frac{15.0}{1.67}\approx8.98\ g/cm^{3}$, which is close to the density of copper.

Step7: Find volume of magnesium

For magnesium, $
ho = 1.74\ g/cm^{3}$ and $m = 78.11\ g$. Using $V=\frac{m}{
ho}$, we get $V=\frac{78.11}{1.74}\approx44.89\ cm^{3}$.

Answer:

1. $0.000000000758$
2. $\frac{365}{6}\approx60.83$ days per year
3. 110 feet per second
4. Approximately $11.16\ cm^{3}$
5. Approximately $75187.97\ cm^{3}$
6. Copper
7. Approximately $44.89\ cm^{3}$