Correct Answer: Six

Solution : The correct option is 6 .

Every sodium (Na) ion in a sodium chloride (NaCl) crystal lattice has six surrounding chloride (Cl) ions, and every chloride ion has six surrounding sodium ions. This arrangement is a result of the ionic bonding between sodium and chloride ions, and it forms a regular, three-dimensional pattern known as a face-centred cubic lattice. Six sodium ions are pulled to and surrounded by six chloride ions in an energetically favourable and stable configuration, and vice versa.