A silicon chip is used in an integrated circuit of a microcomputer has a mass of 5.68 mg. How many Si Atoms are present in this chip.

Okay here is how I worked it. Can someone please tell me if its right?

1 mole of Si = 28.086g = 6.022 x 10^23

5.68mg of Si 1g/1000mg =
.00568g 6.022 x 10^23/28.086 = 1.22 x 10^20 atoms

I do not know if I did that right or not. Can someone please check it for me please?

correct.

:) thanks so converting milligrams to gram was a good idea

Since you chose to use grams for the unit of the molar mass, then you must also choose grams for the mass of the Si chip. That means converting mg to g.

So, it would still be correct if i chose mg for the unit of the molar mass? that way i don't have to convert?

It's true that, although we usually talk about molar mass in grams, we CAN make it mg, or kg, or tons (or any other unit) and adjust our other numbers. For example, try a problem with, "How many grams of O2 are formed from the decomposition of 12.25 g KClO3 by

2KClO3 ==> 3O2 + 2KCl.

Use 122.5 for the molar mass KClO3
Now work the same problem with 10 tons KClO3 at the beginning,
a. convert tons to grams, work the problem, and convert back to grams.
b. just call the molar mass of KClO3 122.5 tons instead of 122.5 grams. You should get the same answer you obtained in a but not go through the conversion both ways.
c. note that 12.25 g KClO3 gives you 4.800 g O2 and 12.25 tons KClO3 gives you (the same number) 4.800 tons O2. using 122.5 g for the molar mass of KClO3 and 32.00 as the molar mass O2.

It's a little risky if you don't have the experience because you may not remember in working a problem that you have or haven't converted. And you may get a problem on an exam where the prof want to see the conversion from tons to grams to tons. But as a shortcut it's a nice thing to know.

Your calculations are almost correct, but there is a small mistake in your units conversion. Let's go through it step by step:

1 mole of Si = 28.086 g = 6.022 x 10^23 atoms

First, let's convert the mass of the silicon chip from milligrams (mg) to grams (g):

5.68 mg * (1 g / 1000 mg) = 0.00568 g

Now, we can calculate the number of moles of silicon in the chip using the molar mass of silicon:

0.00568 g / 28.086 g/mol = 0.000202 mol

Finally, we can calculate the number of silicon atoms using Avogadro's number:

0.000202 mol * (6.022 x 10^23 atoms/mol) = 1.215 x 10^20 atoms

So, you were very close! The correct answer is approximately 1.215 x 10^20 Si atoms in the silicon chip.