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Q. |
Helium gas is used in gas balloons instead of hydrogen gas be-cause it is – |
A. | lighter than hydrogen |
B. | more abundant than hydrogen |
C. | non-combustible |
D. | more stable |
Answer» C. non-combustible | |
Explanation: Because of the Archimedes' principle, a lifting gas is required for aerostats to create buoyancy. Its density is lower than that of air (about 1.29 kg/m3, 1.29 g/L). Only certain lighter than air gases are suitable as lifting gases. Hydrogen and helium are the most commonly used lift gases. Although helium is twice as heavy as (diatomic) hydrogen, they are both so much lighter than air that this difference is inconsequential. Both provide about 9.8 N of lift (1 Newton is the force required to accelerate 1 kg at 1 misec2) per cubic meter of gas at STP. |
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