How many electrons are present in `""_(1)^(2)H,""_(2)HeandHe^(o+)`? Which of these are hydrogen like specis?

Explanation

Hydrogen-like species contain only one electron.
`""_(1)^(2)H` number of protons = 1
= number of electrons
`""_(2)He` : number of protons = 2
= number of electrons
`He^(o+)` : (number of electron in He)-1
= (number of electron in `He^(o+)`)
= (2 - 1) = 1
Thus `""_(1)^(2)HandHe^(o+)` are hydrogen-like species.