Which of the following lacks phosphorus ?
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Answer: D. Steel
Explanation
Steel is an alloy primarily composed of iron and carbon, lacking significant phosphorus content. While trace impurities may sometimes be present, phosphorus is not a foundational component of steel alloys. Manufacturing processes specifically aim to minimize phosphorus levels because it causes unwanted brittleness in steel. Alloys are metallic mixtures composed of two or more elements designed to enhance desired structural properties. Phosphorus is an essential nutrient found abundantly in biological molecules like nucleic acids and bone minerals. Metallurgical refining removes undesirable non-metallic elements to improve the tensile strength of structural steel.
Civil engineering and construction industries rely heavily on high-purity steel for building strong infrastructure. Biochemical analysis frequently distinguishes organic tissues rich in phosphorus from manufactured metal alloys. Materials science studies alloy compositions to control mechanical ductility and prevent structural fatigue failures. Option A is the yolk of an egg, which contains phosphorus-rich phospholipids essential for embryonic cell growth. Option B is bone tissue, which is composed largely of calcium phosphate minerals providing skeletal rigidity. Option C represents neural tissues, which contain high concentrations of phosphorus-containing myelin and phospholipids.
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