If four pounds of a gas occupy 10 ft³, what would be its density and specific gravity?
(a) Density: 0.4 lb/ft³, Specific gravity: 0.1.
(b) Density: 0.4 lb/ft³, Specific gravity: 0.4.
(c) Density: 0.04 lb/ft³, Specific gravity: 0.1.
(d) Density: 0.04 lb/ft³, Specific gravity: 0.4.