In basic materials science and chemical engineering data tables, what is the melting point of elemental sodium at 1 atm (atmospheric pressure), expressed in °C?

Introduction:
The melting point of an element at 1 atm is a fundamental property used in process design, safety assessment, and materials selection. Sodium is a common alkali metal with distinctive thermal behavior that affects storage and handling in reactors and heat-transfer systems.

Given Data / Assumptions:

• Standard pressure is 1 atm.
• We seek the bulk melting point of pure sodium (no alloying, no significant impurities).
• Temperature is to be reported in degrees Celsius.

Concept / Approach:
Sodium is an alkali metal with low melting point compared to most structural metals. Reliable handbooks list its melting point very close to 98 °C (more precisely around 97.8 °C). In engineering calculations, it is typically rounded to 98 °C for convenience, which is sufficiently accurate for most design estimations and operational guidelines.

Step-by-Step Solution:
Identify the standard melting point of sodium at 1 atm from reference data: approximately 97.8 °C.Round appropriately for an MCQ context: 98 °C.Select the option that matches: 98.

Verification / Alternative check:
Multiple materials databases and physical-chemistry handbooks converge on the value near 98 °C for sodium’s melting point under atmospheric pressure, confirming the selection.

Why Other Options Are Wrong:

• 58 °C: Too low, inconsistent with standard data.
• 348 °C and 588 °C: Far above sodium’s known melting range; these are more typical of higher-melting metals or salts.
• 92 °C: Closer but still not the accepted standard value.

Common Pitfalls:
Confusing °C with °F, or mixing sodium’s melting point with those of potassium (lower) or other metals. Another error is quoting values under nonstandard pressures or for sodium alloys rather than pure sodium.

Final Answer:
98