Answer:
The He₂ 2+ ion is more stable since it has a higher bond order (bond order = 1) than the He₂ + ion (bond order = 1/2).
Explanation:
Molecular orbital of He₂⁺

There are two electrons in bonding and 1 electron in antibonding orbital
Bond order =
= 
Molecular orbital of He₂⁺²

There are two electrons in bonding and 0 electron in antibonding orbital
Bond order = 
= 1
So bond order of He₂⁺² is 1 which is more stable than He₂⁺ whose bond order is
.
Because their molecules are more tightly packed. Massdensity = ---------- Volume
So more densely packed molecules means more mass per unit volume. Hence metals are denser than non-metals.
Conversion process of non-organic carbon dioxide into organic compounds by living organisms.
Example: Photosynthesis