which of the following substances contains a nonpolar covalent bond?\nperiodic table of the elements\no…

Explanation:

Step1: Recall bond - type criteria

Non - polar covalent bonds occur between atoms with the same electronegativity. Ionic bonds form between a metal and a non - metal with large electronegativity differences. Polar covalent bonds form between non - metals with different electronegativities.

Step2: Analyze each option

• $\ce{H2O}$: Oxygen and hydrogen have different electronegativities, so the $\ce{O - H}$ bonds are polar covalent.
• $\ce{NaCl}$: Sodium is a metal and chlorine is a non - metal. It is an ionic compound with ionic bonds.
• $\ce{MgF2}$: Magnesium is a metal and fluorine is a non - metal. It is an ionic compound with ionic bonds.
• $\ce{N2}$: Nitrogen is a non - metal. In $\ce{N2}$, the bond is between two nitrogen atoms with the same electronegativity, so it has a non - polar covalent bond.
• $\ce{NH3}$: Nitrogen and hydrogen have different electronegativities, so the $\ce{N - H}$ bonds are polar covalent.

Answer:

$\ce{N2}$