ACrystallization
BFractional distillation
CMagnetic separation
DDistillation
Answer:
B. Fractional distillation
Read Explanation:
The correct method for separating oxygen from air among the given options is (B) Fractional distillation.
Fractional Distillation
This is the most common method for large-scale production of high-purity oxygen and other atmospheric gases. The process involves cooling air to a very low temperature (around -196°C) until it turns into a liquid. At this point, the liquid air is a mixture of nitrogen, oxygen, and other gases. The mixture is then heated, and because each gas has a different boiling point, they vaporize at different temperatures, allowing for their separation. Nitrogen boils off first at -196°C, leaving behind the liquid oxygen, which has a boiling point of -183°C. This method is a type of distillation used to separate mixtures with very close boiling points.
(A) Crystallization: This method is used to purify solids and is not suitable for separating gases.
(C) Magnetic separation: This technique is used to separate materials based on their magnetic properties. Since oxygen is paramagnetic (weakly attracted to a magnetic field) and nitrogen is diamagnetic (repelled by a magnetic field), this method can be used in specialized situations, but it's not a standard industrial process for separating large volumes of air.
(D) Distillation: This is a general term for a separation process. While fractional distillation is a type of distillation, the term "distillation" alone is too broad and often refers to the separation of liquids with widely different boiling points, not the specific process used for cryogenic air separation. Fractional distillation is the precise and correct term.