Which gas has the highest specific gravity among the listed?

Which gas has the highest specific gravity among the listed?

• A. CO2 1.53
• B. NO2 1.6
• C. SO2 2.26
• D. H2S 0.9

Answer: (C)

Specific gravity is the density of a gas relative to the density of air under the same conditions. Gases with SG greater than 1 are heavier than air and tend to settle in low areas; those with SG less than 1 rise and mix higher in the shaft. Among the gases listed, sulfur dioxide has the highest SG, about 2.26. That means it is more than twice as dense as air, so it will accumulate in low spots and pose a greater hazard there. The other gases have lower SG values—carbon dioxide around 1.53, nitrogen dioxide about 1.6, and hydrogen sulfide about 0.9—so they’re not as heavy as sulfur dioxide and don’t settle as readily in the same way. This is why sulfur dioxide is the correct choice for the highest specific gravity in this set.

Specific gravity is the density of a gas relative to the density of air under the same conditions. Gases with SG greater than 1 are heavier than air and tend to settle in low areas; those with SG less than 1 rise and mix higher in the shaft.

Among the gases listed, sulfur dioxide has the highest SG, about 2.26. That means it is more than twice as dense as air, so it will accumulate in low spots and pose a greater hazard there. The other gases have lower SG values—carbon dioxide around 1.53, nitrogen dioxide about 1.6, and hydrogen sulfide about 0.9—so they’re not as heavy as sulfur dioxide and don’t settle as readily in the same way. This is why sulfur dioxide is the correct choice for the highest specific gravity in this set.