In which substance does sharing of electrons between two atoms occur?

a. so4 2−

b. fe

c. nacl

d. he

i think its a. correct me if i am wrong.

A. SO4 2−

Explanation:

                           SO₄²⁻

A covalent bond is a bond that forms from sharing of electrons between two atoms. Here, the two atoms combined must have a very low electronegative difference between them, usually 0. Electronegativity deals with the tendency of an atom to attract electrons to itself.

Oxygen and sulfur shows similar tendencies. Since the two atoms shows a strong affinity for their valence electrons in order to complete the octet. This will lead to the eventual sharing of the valence electrons.

Explanation:

A covalent bond is formed when an element shares its valence electron with another element. This bond is formed between two non metals.  Example:

An ionic bond is formed when an element completely transfers its valence electron to another element. The element which donates the electron is known as electropositive element and the element which accepts the electrons is known as electronegative element. This bond is formed between a metal and an non-metal. Example:

has metallic bonds and helium has dispersion forces.

pure substance: iron,copper

impure substance: water,charcoal