A.
B. and C. both are missing commas in their sentences. A doesn't require a comma anywhere
A. Posters about safety hangs in every office in Town Hall.
Answer:
A
Explanation: because it is a fact with actual data while the others are opinions
Find the moles of Boron and of Chlorine:
Assume there are 100 g of the compound in all
Boron: 9.224% --> .09224 (convert percent to decimals)
.09224*100g = 9.224g Boron (theoretical amt)
9.224g* 1mol/10.81g (molar mass Boron) = .8533 moles Boron