Solution
= Solution
This statement is true. If $(x_n)$ is dense in $B_X$, then on $B_{X^*}$ the weak-star topology is induced by a metric such as
$$
d(f,g)=\sum_{n\geq1}2^{-n}
\frac{|(f-g)(x_n)|}{1+|(f-g)(x_n)|}.
$$
The <Banach-Alaoglu theorem> makes this metric space compact, and every compact metric space is sequentially compact.