Answer : Option A) [tex] O_{2} [/tex]
Explanation : From the given options;
A) [tex] O_{2} [/tex] is the molecule which forms double bonds with own atom and becomes stable. It covalently shares the two valence electrons in the valence shell and becomes an octet.
B)[tex] H_{2}O [/tex] the water molecule does not forms double bond between H atom and O atom as the valency of oxygen is two and hydrogen is one. So two atoms of H forms a single bond with one atom of O.
C) [tex] Cl_{2} [/tex] molecule shares a covalent bond with the other atom of Cl. This does not forms a double bond as only one electron is needed for Cl to attain the octet state.
D) [tex] NCl_{3} [/tex] The N atom has 3 electrons for donating, which is fulfilled by each of Cl atoms as they need only one electron to be an octet. It forms a single bond as there are no lone pairs left to form a double bond.
Hence, the correct answer is [tex] O_{2} [/tex] molecule.
