Match each mixture or suspension in List I with the most appropriate physical separation t… — JAMB UTME

Match each mixture or suspension in List I with the most appropriate physical separation technique based on component properties in List II.

A dry solid mixture of ammonium chloride ( $NH_4Cl$ ) and sodium nitrate ( $NaNO_3$ )Sublimation via gentle heating and vapor condensation
A industrial scrap mixture containing cobalt powder and powdered brassMagnetic separation utilizing a ferromagnetic field gradient
A colloidal precipitate suspension of cellular organelles in a biochemical buffer solutionHigh-speed centrifugation based on differential particle density and sedimentation rate
A solid mixture of iodine crystals and fine silica sandSublimation via direct phase transition of iodine without liquid formation

Answer

The correct pairings match: ammonium chloride and sodium nitrate with sublimation via gentle heating; cobalt powder and brass with magnetic separation; cellular organelles suspension with high-speed centrifugation; and iodine crystals and sand with iodine sublimation.

Each mixture is paired with the separation technique that targets a distinct physical property difference: sublimable volatile solids (

NH_4Cl

, iodine) separated by sublimation; ferromagnetic cobalt separated by magnetization; and fine organelle colloidal suspensions separated by high-speed centrifugation.

Step-by-Step Solution

Analyze the physical properties of the components in the mixture of ammonium chloride and sodium nitrate.

Ammonium chloride (

NH_4Cl

) sublimes readily when heated, while

NaNO_3

has a high melting point and does not sublime.

Difference in volatility and sublimability allows ammonium chloride to be isolated as a sublimates deposit.

Evaluate the magnetic properties of cobalt powder and brass.

Cobalt is ferromagnetic and strongly attracted to a magnetic field, while brass (alloy of Cu and Zn) is non-magnetic.

A magnetic separator can selectively withdraw cobalt from the non-magnetic brass powder.

Determine the physical behavior of fine organelle suspensions.

Microscopic cellular organelles suspended in liquid buffers experience Brownian motion and take extremely long periods to settle under normal gravity.

Applying high rotational speed (centrifugal force) accelerates sedimentation according to particle density and mass differences.

Examine the mixture of iodine crystals and silica sand.

Iodine transitions directly from solid to vapor upon heating (

I_{2(s)} \rightarrow I_{2(g)}

) and re-crystallizes on a cold condenser surface, whereas silica sand (

SiO_2

) is heat-stable and non-volatile.

Sublimation isolates iodine in high purity while sand remains in the heating container.

Key Concept

Physical Separation Techniques: Sublimation, Magnetization, and Centrifugation

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics