Question

Need help with 3 4 and 5
You can do one at a time or only answer one

Answer 1

I'll do one and you can use similar techniques to hopefully solve the other three.

3) We are given an amount of atoms, and we are asked to find the weight in grams. So we are going to use Avogadro's number to convert atoms to moles:

$\frac{1mole}{6.022*10^{23}atoms} *[6.72*10^{27} atoms]=1.12mol_{C}$

Then we need to use the molar weight of carbon (C) found on the periodic table. The molar weight of carbon is 12.01 g/mol. So let's do the same thing and cancel out moles to solve for grams:

$\frac{12.01g}{1mol}*1.12mol=13.45g_{C}$

So now we know that the given amount of carbon atoms is equal to 13.45g.