Which of the following functions is not periodic

Period of $\frac{2^x}{2^{\left[x\right]}}$ is 1. Period of ${\sin }^{-1}\left\{x\right\}$ is 1.

Period of ${\sin }^{-1}\left(\sqrt{\cos x}\right)$ is $2\pi$ where as ${\sin }^{-1}\left(\cos x^2\right)$ is non-periodic.