Li+ express your answer in complete form, in order of increasing orbital. for example, 1s22s2 would be entered as 1s^22s^2.

Lithium with symbol Li has an atomic number of 3.
First energy shell has s orbital and can hold up to 2 electrons. Second energy shell has s orbital and p orbital and altogether 2nd energy shell can hold upto 8 electrons.
Li electronic configuration is 1s^2 2s^1
Li has one electron in the outer shell, to become stable it loses that electron.
As Li loses one electron, its net charge becomes +1

electronic configuration of Li⁺ - 1s^2 

Yes it would be a physical change.

The teacher is mostly talking about the distillation of a mixture