Question

Question #76833

Answer 1

`"0.56 h"`

Explanation:

Start by converting the volume of the vessel from liters to milliliters by using the fact that

`color(blue)(ul(color(black)("1 L" = 10^3color(white)(.)"mL")))`

In your case, the vessel contains exactly `"1.0 L"` of water, so you can say that it contains `1.0 * 10^3` `"mL"` of water.

Now, you know that `"1.00 mL"` of water contains `20.0` drops of water. Use this conversion factor to convert the volume of the vessel from milliliters to drops

`1.0 * 10^3 color(red)(cancel(color(black)("mL"))) * "20.0 drops"/(1.00color(red)(cancel(color(black)("mL")))) = 20.0 * 10^3color(white)(.)"drops"`

The problem tells you that you can count the drops at a rate of `"10.0 drops/s"`, so use this conversion factor to find the total time needed to count all the drops present in the vessel

`20.0 * 10^3 color(red)(cancel(color(black)("drops"))) * "1 s"/(10.0color(red)(cancel(color(black)("drops")))) = 2.00 * 10^3color(white)(.)"s"`

Finally, use the fact that

`color(blue)(ul(color(black)("1 h = 3600 s")))`

to convert the time from seconds to hours.

`2.00 * 10^3 color(red)(cancel(color(black)("s"))) * "1 h"/(3600color(red)(cancel(color(black)("s")))) = color(darkgreen)(ul(color(black)("0.56 h")))`

The answer is rounded to two sig figs, the number of sig figs you have for the volume of the vessel.