Question

Question #e0b0f

Answer 1

oxygen(O) forms anion

Explanation:

1.Argon(Ar): is an inert gas and hence doesn't form an ion.

2.Potassium(K) (at no:19): is in deficiency of one electron to achieve octet rule and hence donates an electron.

3.Aluminium(Al)(at no 13): is in deficiency of one electron to achieve octet rule and hence donates an electron.

4.Oxygen(O): is in deficiency of 2 electrons and to achieve octet rule it takes 2 electrons

***you might get a doubt that potassium and aluminium are also in need of electron but don't form an anion that is because their outer electronic configuration is `4s^1` and `3p^1` respectively. Since in potassium it is a s-orbital it has low energy and it prefers to lose an electron rather than to gain one.even in aluminium it is easy to lose 1 electron than to gain 5.