Final answer:
The ion that is paramagnetic from the given list is Ni²⁺ because it has two unpaired electrons in its electron configuration, causing it to exhibit paramagnetic properties.
Step-by-step explanation:
To determine which of the given ions is paramagnetic, we need to look at their electron configurations and identify if there are any unpaired electrons. Paramagnetism occurs in ions that have at least one unpaired electron.
- V⁵⁺ has a 3d0 electron configuration due to all its five 3d electrons being removed, which makes it diamagnetic.
- Mn⁷⁺ has a 3d0 electron configuration as it has lost all seven of its 3d electrons, making it diamagnetic.
- Sc³⁺ also has a 3d0 electron configuration after losing its three 3d electrons, which results in it being diamagnetic.
- Ni²⁺, however, has a 3d8 electron configuration, meaning there are two unpaired electrons, which makes it paramagnetic.
- Ti⁴⁺ has a 3d0 electron configuration as well, leading to diamagnetic behavior.
Therefore, the ion that is paramagnetic out of the options given is Ni²⁺ because it has unpaired electrons in its d orbitals.