Which pair correctly identifies the two solid allotropes of tin?

Which pair correctly identifies the two solid allotropes of tin?

• A. Red tin and blue tin
• B. White tin (beta tin) and gray tin (alpha tin)
• C. Beta tin and delta tin
• D. Tin oxide and tin sulfide

Answer: (B)

Allotropes are different crystal forms of the same element that can exist under the same pressure. Tin has two solid allotropes at ambient pressure: white tin, known as beta tin, and gray tin, known as alpha tin. White tin is the metallic, conductive form that’s stable at higher temperatures, while gray tin is the softer, brittle form that becomes stable as the temperature drops below about 13.2°C and has a diamond-like crystal structure. Gray tin also expands upon cooling, a phenomenon linked to tin pest. Therefore, the pair that correctly identifies the two solid allotropes is white tin (beta tin) and gray tin (alpha tin). The other options refer to names that aren’t standard allotropes or describe compounds (tin oxide, tin sulfide), or include a less relevant high-temperature phase (delta tin) rather than the two common solid allotropes.

Allotropes are different crystal forms of the same element that can exist under the same pressure. Tin has two solid allotropes at ambient pressure: white tin, known as beta tin, and gray tin, known as alpha tin. White tin is the metallic, conductive form that’s stable at higher temperatures, while gray tin is the softer, brittle form that becomes stable as the temperature drops below about 13.2°C and has a diamond-like crystal structure. Gray tin also expands upon cooling, a phenomenon linked to tin pest. Therefore, the pair that correctly identifies the two solid allotropes is white tin (beta tin) and gray tin (alpha tin). The other options refer to names that aren’t standard allotropes or describe compounds (tin oxide, tin sulfide), or include a less relevant high-temperature phase (delta tin) rather than the two common solid allotropes.