An atom which has lost one electron would be

Which one of the following groupings represents a collection of isoelectronic species?

Which of the following is $NOT$ a hydrogen-like species?

The number of electrons plus neutrons in ${}_{19}^{40} K^{+}$ is $.....$

Which of the following is correct?

Provide the symbol,name,atomic number $(Z)$,mass number $(A)$,and the number of electrons $(e)$,protons $(p)$,and neutrons $(n)$ for elements with atomic numbers $1$ to $10$.