Answer
See graph; asymptote: $y=0$
Domain: $(-\infty,\infty)$ and range: $(0,\infty)$
Work Step by Step
Step 1. Start from the original function $f(x)=e^x$ shown as the green curve in the figure.
Step 2. To obtain the new curve of $g(x)=\frac{1}{2}e^{x}$, shrink the original vertically by a factor of 2 to get the red curve as shown.
Step 3. We can identify the asymptote as $y=0$
Step 4. We can determine the domain as $(-\infty,\infty)$ and range as $(0,\infty)$