b) The molar mass of gold is 0.197kg. Calculate the mass of a gold atom, to 3 SF. (1 mole = 6x1023)

Thanks Alan.   

Just divide the mass by Avogadro's number (given in the question as 6*10²³)

$$\frac{0.197}{6\times 10^{23}}= 0.03283\times 10^{-23}kg$$

or 

$$3.28\times 10^{-25}kg$$

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Thanks Alan,

So is there always  6x10^23 atoms in a mole (of anything) ?

Can you (or someone else) tell us a little about the significance of Avogadro's number? (Only if  is relatively easy to do.  )

By definition a mole is Avogadro's number worth!  

Avogadro's number is more precisely given by: 6.02214129×10²³ 

Have a look at http://en.wikipedia.org/wiki/Avogadro_constant for more details.

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