8.2 grams = 1 mol
Na ________
22.99 grams
First multiply the value of 8.2 to 1. Then divide by the value of 22.99 to determine the number of moles of sodium present in the 8.2 gram sample.
Then use the following equation to solve for sodium atoms.
Number of moles of Na • Avogadro Number = Number of sodium atoms.
0.3566782 • (6.02 X 10^23). = 2.1472 X 10 ^ 23. Or 2.15 X 10 ^ 23.
The answer is the second option - 2.15 X 10 ^ 23.
6.7 x -2.3
You would multiply this just like any other multiplication question.
There is some work of course, but I'm not going to write it out here...
You are going to end up with -15.41, which is already rounded to the nearest hundredth.
Hope this helped :)
The area of D is given by:

The average value of f over D is given by: