Which of the following statements are correct?

$\mathrm{Li}{}^{+}$ is smaller than $\mathrm{Na}{}^{+}$, so $\mathrm{LiCl}$ is more covalent. $\mathrm{Cu}{}^{+}$ has an $18$-electron core and polarises more than $\mathrm{Na}{}^{+}$. $\mathrm{Sn}{}^{4+}$ is smaller and more highly charged than $\mathrm{Sn}{}^{2+}$. $\mathrm{Ca}{}^{2+}$ is far larger than $\mathrm{Be}{}^{2+}$, so $\mathrm{CaCl}{}_2$ is less covalent and statement 3 is false.