A comparison of density values obtained by X-ray diffraction reveals that the percentages of vacant sites in aluminum (Al) are 0.0700% at 923 K and 0.0090% at 757 K.

Given this data, determine the number of vacant sites per cm3 at 550 K.

Express your answer as vacancies/cm3.

7.4*10^18 <--- this answer is wrng. . plz help.

3 answers

then somethings off..i got that ticked...it says 'The grader on this problem has been corrected, and the number of attempts has been increased to 10', so the answer has changed i guess..but why still i got the green tick??...
Me too got green tick only.
Luk in 3.091 final 2011. same question and same answer.. method given.