Answer: Ga > Ca > K
Step-by-step explanation:
Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.
The electrons are filled according to Afbau's rule in order of increasing energies. The metals tend to get stable by losing electrons to attain noble gas configuration.
![K:19:1s^22s^22p^63s^23p^64s^1](https://img.qammunity.org/2021/formulas/chemistry/college/3jkwmcapn3eadaayipwwz6p3sk35mwiyw0.png)
![K^+:18:1s^22s^22p^63s^23p^6](https://img.qammunity.org/2021/formulas/chemistry/college/wzohqf5kvnkuirto95mz6sr55sc1vpr2n7.png)
![Ca:20:1s^22s^22p^63s^23p^64s^2](https://img.qammunity.org/2021/formulas/chemistry/college/zec4p8fqk6a2uicqv2h8d2t278yyfq27x9.png)
![Ca^(2+):18:1s^22s^22p^63s^23p^6](https://img.qammunity.org/2021/formulas/chemistry/college/oqakzb2xhbwc7g6o96uyefm8budc38f1pl.png)
![Ga:31:1s^22s^22p^63s^23p^64s^23d^(10)4s^24p^1](https://img.qammunity.org/2021/formulas/chemistry/college/zxk7qftu0k9ie5att90g75ha13eyznu8d5.png)
![Ga^(3+):28:1s^22s^22p^63s^23p^64s^23d^(10)](https://img.qammunity.org/2021/formulas/chemistry/college/i3h83nvmtl7g4l8r2pjivxh6eqoyyc8oau.png)
Thus gallium (Ga) loses three electrons, Calcium (Ca) loses 2 electrons and Potassium (K) loses one electron.