Sodium's low melting point identifies its position

Steps:

• Sodium (atomic number 11) is an alkali metal with a melting point of 98°C, low due to weak interatomic forces.
• Consecutive elements around it (e.g., Ne to Cl) show a pattern: very low for gases, low for Na, high for metals like Mg/Al/Si, then dips for nonmetals.
• Examine the diagram for a low melting point peak after a noble gas minimum and before a metallic rise.
• Match this to option C, which positions sodium correctly in the sequence.

Why C is correct:

• Alkali metals like sodium have low melting points from delocalized electrons forming weak bonds, per metallic bonding theory.

Why the others are wrong:

• A: Too high, matches refractory metals like Al or Si.
• B: Too low, fits noble gas like Ne.
• D: Matches nonmetal like P or S with moderate mp.

Final answer: C