$\exp$ is an isomorphism $(\mathbb{R},+)\to(\mathbb{R}^+,\cdot)$

Consider the three groups $G_1=\langle\mathbb{C}^*,\cdot\rangle$, $G_2=\langle\mathbb{R},+\rangle$ and $G_3=\langle\mathbb{R}^+,\cdot\rangle$. Which of the following is true?