(i) Prove that End $\left(\mathbb{Z}\left(p^{\infty}\right)\right) \cong \mathbb{Z}_{p}$ as rings, where $\mathbb{Z}_{p}$ is the ring of $p$-adic integers.
$$
\left(a_{0}, a_{1}, a_{2} \ldots, \mid p a_{0}=0, p a_{n}=a_{n-1} \text { for } n \geq 1\right)
$$
(ii) Prove that the additive group of $\mathbb{Z}_{p}$ is torsion-free.