Elements of which one of the following pairs form ionic bonds between them when combined together ?

Ionic bonds are formed through the transfer of electrons from a metal to a non-metal, resulting in electrostatic attraction between oppositely charged ions [t1, t3]. Sodium (a metal) has one valence electron, while chlorine (a non-metal) has seven. During their reaction, sodium transfers its single outer electron to chlorine, forming a sodium cation (Na+) and a chloride anion (Cl-) [c2, t2, t5]. These ions are held together by strong electrostatic forces to form sodium chloride (NaCl) [c2, t7]. In contrast, pairs like carbon and hydrogen, nitrogen and hydrogen, or two chlorine atoms form covalent bonds by sharing electrons to achieve stable configurations [c1, c4, t4]. Carbon compounds specifically are non-conductors, indicating they do not produce ions through electron transfer [c3]. Therefore, only the sodium and chlorine pair forms an ionic bond.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.3 HOW DO METALS AND NON-METALS REA ALS REACT? > p. 47
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.1 BONDING IN CARBON – THE COVALENT BOND > p. 60
3. [3] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > What you have learnt > p. 77