Concept:
Color in glass is produced by adding small amounts of metal oxides. Different oxides produce different colors.
Step 1: Chromium oxide is a common coloring oxide used in glass.
\[
Cr_2O_3=\text{Chromium oxide}
\]
Step 2: Chromium oxide generally gives green color to glass.
Step 3: Cupric oxide may give blue-green color depending on glass composition, but the standard green colorant among the given options is chromium oxide.
Step 4: Selenium is commonly used for red or pink shades and magnesium oxide is not used as the main green colorant.
Therefore, the oxide which imparts green color in glass is:
\[
\boxed{\text{Chromium oxide}}
\]