Final answer:
The formula that matches the name barium nitrate is Ba(NO3)2, which is option b.
Step-by-step explanation:
The correct formula for barium nitrate is Ba(NO3)2. When naming chemical compounds, the general rule is to write the name of the metal cation followed by the name of the nonmetal anion with the appropriate suffix. Barium is a metal with a 2+ charge, and the nitrate ion is NO3− with a 1- charge. Because barium has a 2+ charge, two nitrate ions are needed to balance the charges, resulting in the formula Ba(NO3)2.