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Answer 1 · 2017-09-12T04:57:26

#2.020* 10^23# atoms

First, convert grams of chromium to moles:

#17.441 "g Cr" ("1 mol"/ "51.996 g Cr") = 0.335# mol Cr

Then convert from moles to atoms using Avogadro's Number:

#0.335 "mol Cr" ("6.022*10^23 atoms"/ "1 mol") = 2.020*10^23# atoms Cr

Answer 2 · 2017-09-12T04:58:27

#"Number of chromium atoms"~=2xx10^23#

We work out (i) the molar quantity of chromium....

#"Moles of Cr"# #=# #(17.441*g)/(51.9961*g*mol^-1)#

#=0.3354*mol#.

And (ii) we know that a mole specifies Avogadro's number of molecules, i.e. #6.022xx10^23*mol^-1#, and so we take the product....

#=0.3354*molxx6.022xx10^23*mol^-1=??#