Answer:
199.26 or with sig figs 2.0 x 10^2
Explanation: you take the # of molecules and divide it by avagadros number which is 6.022141 x 10^23
The answer is 0.492 because there are 100 meters in a hectometer, and 49.2/100 is 0.492
Unit cells.
They are the smallest group of atoms that take form of a crystal and can repeat in 3 dimensions.
1 B2Br6 + 6 HNO3 = 2 B(NO3)3 + 6 HBr