<span>Fluorine ONLY form\s an ion with a -1 charge. The other three are metals, and metals for positively charged ions.</span>
Based upon Max Planck's theory of black-body radiation, Einstein theorized that the energy in each quantum of light was equal to the frequency multiplied by a constant, later called Planck's constant. A photon above a threshold frequency has the required energy to eject a single electron, creating the observed effect.
Answer : If we consider the molecule of oxygen gas which in diatomic state, is bonded to other atom which is of same element this is called as homonuclear.
While in HCl there is a heteronuclear bonding observed because there are two different elements getting involved in the bond formation, also it creates a electrovalent species in itself and makes it more polar. They are creating a dipole moment by separating different charges in the molecule which cause it to get tightly bonded with each other.