Chemistry: Matter and Separation Techniques MCQ paper 2

Dissolving salt in water is a physical change, as no new substances are formed; the salt can be recovered by evaporation.

A compound is a pure substance formed when two or more elements chemically combine in fixed proportions, resulting in new chemical properties.

Centrifugation uses centrifugal force to separate solids from liquids in a colloidal suspension by causing the solid particles to settle at the bottom.

Vaporisation occurs when a liquid turns into a gas at its boiling point. This includes both boiling and evaporation, but at the boiling point, it specifically refers to the rapid conversion to gas.

Chromatography is a technique used to separate components of a mixture based on differences in their movement through a medium. It is effective for separating liquids.

Fractional crystallization separates solids based on their different solubilities in a solvent, allowing for the recovery of multiple solids.

Fractional distillation is used to separate mixtures of liquids with different boiling points, such as the various components of petroleum.

Centrifugation is a technique that uses rapid spinning to separate components of blood based on their density. Blood cells settle at the bottom, while plasma remains on top

the molecule is the smallest particle of a compound which is capable of independent existence. An atom is the smallest unit of a compound capable of taking part in a chemical reaction

Dissolution: Refers to the process of a substance dissolving in a solvent, not a separation method

Boiling Point: Nitrogen and oxygen are separated from air through a process called fractional distillation. This method takes advantage of the different boiling points of these gases. Nitrogen has a boiling point of approximately -196°C, while oxygen has a boiling point of approximately -183°C. By cooling air and then distilling it, these gases can be effectively separated.

A chemical equation describes a chemical reaction rather than a physical property used for separation. Properties like color, size, and density are often used to separate mixtures.

Distillation is used for separating components of a liquid mixture, not specifically for recovering solids from liquids.

Bronze is an alloy a mixture of copper which is the solvent and tin which is the solute. Ie tin dissolved in copper. Bronze typically consists of about 90% copper and 10% tin,The addition of tin to copper improves the strength, corrosion resistance, and overall durability of the metal, making bronze suitable for various applications, including tools, weapons, and sculptures though the proportions can vary.

Sugar dissolves in water while sulfur does not. The mixture can be filtered to remove sulfur, and the sugar solution can then be evaporated to recover sugar.

Distillation is effective for separating ethanol and water due to their different boiling points.

Fractional distillation separates liquid mixtures based on differences in boiling points and densities.

Sublimation is a method that can separate solids based on their ability to transition directly from solid to gas. For example, separating iodine from salt.

This statement is incorrect because physical changes do not produce new substances; they only change the state or appearance of a substance. Chemical changes result in new substances being formed.

Crystallization is specifically used to separate solids from solutions, not for separating solid mixtures directly.

Chromatography relies on the different adsorption properties of substances to separate them as they move through a medium

Fractional distillation separates petroleum into its various components based on boiling points

Mercury is a pure substance, while the others are mixtures of various components.

Distillation is primarily used for separating liquids based on boiling points, not for separating solids.

A separating funnel is ideal for separating immiscible liquids like kerosene (a hydrocarbon) and water.

Distillation separates liquids based on their boiling points. It is commonly used to purify liquids or separate liquid mixtures.

Hand-picking: This method relies on the physical appearance (color, size) of the components to separate them manually.Centrifugation: This technique separates components based on their mass and density by spinning them at high speeds.Distillation: This method separates substances based on differences in their boiling points, not their color or mass.Filtration: This technique separates solids from liquids or gases based on particle size.

This is a chemical change known as slaking, where quicklime (calcium oxide) reacts with water to form calcium hydroxide, resulting in a new substance.

Freezing ice-cream is a physical change because it involves a change in the state of matter from liquid to solid without altering the chemical composition of the ingredients. The ice-cream can be melted back to its original state.

burn is a chemical reaction in which a substance combines with oxygen, often resulting in a change in the chemical composition and the formation of a new substance.

Explanation: Ammonium chloride undergoes sublimation when heated, converting directly from solid to gas without becoming liquid. The white deposit observed is likely the result of gas cooling and solidifying.

Residue refers to what is left behind after a process, whereas ion, atom, and molecule are all fundamental constituents of matter.

Molecular number is not a property typically used in the physical separation of mixtures. Properties like weight, solubility, and melting point are commonly used

The change in color of zinc oxide with heating and cooling is a physical change, as it does not involve a change in the chemical composition of the substance

Kerosene is a hydrocarbon fuel that does not contain oxygen in its composition.

When warm air meets the cold surface of the bottle, water vapor condenses into droplets.

Crystallization is a method used to separate a soluble solid from a solution by forming solid crystals, typically by evaporating the solvent.

In an aqueous mixture of sodium chloride (salt) and sand, sand is insoluble in water. When you perform filtration, the sand (solid) will remain on the filter paper, while the sodium chloride (dissolved in water) will pass through as part of the filtrate. Afterward, you can obtain pure sodium chloride by evaporating the water from the filtrate.

Gravity is a force and not a separation method itself. Seiving, centrifugation, and chromatography can involve separation based on particle size.

Distillation is the best method to separate water from a sugar solution, as it uses differences in boiling points to evaporate the water, leaving the sugar behind.

Chromatography separates components of a mixture based on their different affinities to a stationary phase and a mobile phase, making it effective for colored substances.

Blood is a mixture because it contains various components, including red blood cells, white blood cells, platelets, and plasma, which are not chemically bonded and retain their individual properties. Sand is also a mixture, but the question specifies "an example," so blood is a more complex example.

This reaction involves combustion, which is a chemical change that results in the formation of new substances (ash, gases) from the original materials (wood)

Entropy is a measure of disorder or randomness in a system. As temperature increases, particles move more rapidly and the disorder in the system increases.

A separating funnel is specifically designed to separate two immiscible liquids based on their different densities.

This statement is incorrect. An ion is formed when an atom gains or loses electrons, but the number of electrons gained or lost is equal to the ion’s charge, which corresponds to its valency, not twice its valency

Crystallization allows for the recovery of solid solutes from a solution while leaving the solvent intact.

Distillation separates components of a mixture based on differences in boiling points, not particle size. Other methods like sifting, filtration, and centrifugation can involve particle size.

Sublimation is the process where a solid transitions directly to gas without becoming liquid.