Answer
$A_2^+$ has a baryon number of $0$
Work Step by Step
$A_2^+ \rightarrow \rho^0+\pi^+$
$A_2^+ \rightarrow \pi^+ + \pi^- +\pi^+$
On the right side of this process, there are three spin-zero mesons.
Each meson has a baryon number of $0$
According to the baryon number conservation law, $A_2^+$ also has a baryon number of $0$.
