MOHON DIBANTU PLISS.​

Massa rata-rata 1 atom Br =
(massa atom B-10 + massa atom B-11) / jumlah total

= (19,8% x 10,0129) + (80,2% x 11,0093) / 100%
= (1,98 + 8,82) / 100%
= 10,8

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