Science M.C.Q-[Che-1M]

3. Distillation

2. Simple distillation.

Explanation:

In the mixture of iodine and alcohol, both are miscible. So, distillation process is used to recover both the components.

2. These are homogeneous mixture and can be classified as metallic alloys

Explanation:

White gold used in jewellery contains two elements, gold and palladium. A jeweller has two different samples that are both identical in appearance and have a uniform composition throughout. These samples are known as homogeneous mixture and can be classified as metallic alloys.

4. Tyndall effect

4. Air is a heterogeneous mixture

Explanation:

All elements and compounds are homogeneous, as they are pure substances.

A mixture can be homogeneous or heterogeneous.

So, options A, B and C are correct statements.

3. Chromium.

Explanation:

Chromium does not have magnetic property. Therefore, it will not be attracted by a magnet.

4. Milk

Explanation:

A solution is a homogeneous mixture of two or more components. Brass (alloy), lemonade and saltwater are solutions. 

Milk is a colloid of fat globules dispersed in water.

3. Path of light is visible in solution

Explanation:

A solution is a special type of homogeneous mixture.

Solutions are homogeneous because the ratio of solute to solvent remains the same throughout the solution even if homogenized with multiple sources, and stable because.

The solute will not settle out after any period of time, and it cannot be removed by a filter or a centrifuge.

This type of mixture is very stable, i.e., its particles do not settle, or separate.

As a homogeneous mixture, a solution has one phase (liquid) although the solute and solvent can vary:

for example, salt water. In chemistry, a mixture is a substance containing two or more elements or compounds that are not covalently bound to each other and which retain their own chemical and physical identities; a substance which has two or more constituent physical substances.

This doesn't scatter light the path of light is visible in solution.

3. Gallium.

Explanation:

Boron, silicon and germanium are metalloids. Gallium is a metal.

3. Sublimation of naphthalene.

Explanation:

Sublimation of naphthalene is not a chemical change because it only allows naphthalene to change its state from solid to vapour. No new compound is formed and the vapour can again be condensed to solid form.

3. Chalk powder and water mixture.

Explanation:

Chalk in water will most likely scatter the beam of light when passed through it because it forms a suspension.

1. Mud in water

Explanation:

Saltwater is a solution of salt in water in which the particles do not settle own. Blood is a natural colloid, where particles do not settle down.

But mud in water is a suspension as particles are large and heavy enough to settle down and separate from the solution when the solution is kept undisturbed for some time.

1. Sugar sol

Explanation:

True Solution is a homogeneous mixture of two or more substances in which substance dissolved (solute) in solvent has the particle size of less than 10 - 9 m or 1 nm.

Simple solution of sugar in water is an example of true solution. Particles of true solution cannot be filtered through filter paper and are not visible to naked eye.

Colloidal Solution is a heterogeneous mixture in which particle size of substance is intermediate of true solution and suspension i.e. between 1-1000 nm.

Smoke from a fire is example of colloidal system in which tiny particles of solid float in air. Just like true solutions, Colloidal particles are small enough and cannot be seen through naked eye.

They easily pass through filter paper.

But colloidal particles are big enough to be blocked by parchment paper or animal membrane.

blood, starch, ink : Colloidal Soln.

sugar sol., salt sol : true soln.

3. Dogfish.

Explanation:

Jellyfish or jellies are approximately cylindrical vase shaped individuals of phylum-Cnidaria. These are free swimming marine animals consisting of a gelatinous umbrella shaped bell (pulsate for locomotion) and tentacles (to capture prey). Starfish are star shaped echinoderms. These are marine invertebrates which have a central disc and five arms, (tube feet for locomotion) Scoliodon (dog fish) belongs to the class-Chondricythes, i.e., pisces. These fishes are known as dog fish due to their, ability to smell. Lepismasacharina commonly known as silver fish is small wingless insect belongs to phylum- Arthropoda.

4. All of these

2. Helium (He)

Explanation:

4. These are homogeneous in nature

Explanation:

In colloidal solution, a material is evenly suspended in a liquid, e.g., milk or oil in water is a colloidal solution which is present in two phases in heterogenous phase, e.g., foams, emulsions, sols.

2. 204g

Explanation:

Solubility of a substance in water is defined as the maximum amount of solute that can be dissolved in 100g of water at a given temperature. The solubility of sugar in water at 20°C is 204g.

2. Evaporation

Explanation:

Seawater is trapped in large, shallow pools and allowed to stand there.

The sun’s heat evaporates the water slowly, and common salt is left behind.

This salt is further collected, purified, and packed for domestic use.

The concentrated brine precipitates the salt, which is then gathered by mechanical harvesting machines.

Any impurities that may be present in the brine are drained off and discarded before harvesting.

Preparation of salt from seawater involves evaporation in which water undergoes evaporation leaving behind salt.

3. Sand and sulphur.

Explanation:

Mixture of sand and sulphur cannot be separated by using water as a solvent because both are insoluble in water.

1. Compounds have fixed composition.

Explanation:

A chemical compound is a new substance that forms when atoms of two or more elements react with one another. A compound that results from a chemical reaction always has a unique and fixed chemical composition. The substances in the compound can be separated from one another only by another chemical reaction.

1. It is attracted by magnet.

Explanation:

It is the property of iron to get attracted towards a magnet. In a mixture, the properties of the constituent elements do not change, so the iron particles get attracted towards the magnet.

1. Seperating funnel

Explanation:

We can separate them using separating funnel because the two are immiscible and mercury is denser than water.

4. All of these

4. It is soluble in water.

Explanation:

Sulfur is a soft, pale yellow, odorless, brittle solid. It is insoluble in water, but soluble in carbon disulfide. It burns with a blue flame, oxidizing to sulfur dioxide. Sulfur exists in several crystalline and amorphous allotropes.

4. None of the above

4. Milk

Explanation:

Milk is a colloid and is a mixture of fat dispersed and suspended in water.

Suspension is distinguished from colloids by larger particle sizes which settle down when the solution is kept undisturbed, which is the case with the solutions mentioned in A, B and C.

3. Pure Milk

Explanation:

Gold (Au) is found in its pure form in nature. 

Glucose is a naturally occurring sugar with fixed composition and chemical formula C₆​H1₂​O_6​. It is found in its pure form in milk, wheat and many fruits.

Water in its pure form is found in nature with chemical formula H₂​O.

Milk is a heterogeneous mixture of fat (which is a form of ester) and sugar (a form of carbohydrate) and hence is not a pure substance like an element or a compound.

4. Shaving cream.

Explanation:

Shaving cream is not an emulsion but foam.

3. Silica.

Explanation:

Silica is a compound made up of Si(silicon) and O(oxygen) and chemically called Silicon dioxide.

3. Alcohol.

Explanation:

Air, kerosene oil and petrol are mixtures of various compounds of carbon and hydrogen (called hydrocarbons). Alcohol is a compound and not a mixture.

4. Sublimation

Explanation:

A mixture of ammonium chloride and potassium chloride can be separated using the process of sublimation.

You must also note that both these substances are sublimable.

This technique is quite feasible in this case as the sublimable temperatures of ammonium and potassium chloride differ widely.

Between the two, ammonium chloride has lower sublimable temperature.

Therefore, it sublimes first followed by potassium chloride.

3. True solution

Explanation:

A true solution is a homogeneous mixture of two or more substances with a particle size of less than 10^−9m or 1 nm dissolved in the solvent.

A suspension is a heterogeneous mixture in which particles down mixture upon standing, with particle size being over 1000 nm.

A colloid is a heterogeneous mixture in which the dispersed particles are intermediate in size between those of a true solution and suspension i.e (1−1000 nm).

3. Air.

Explanation:

Air is a homogeneous mixture of different gases. Hence, it does not have a fixed melting or boiling point.

3. Hydrogen.

Explanation:

Hydrogen cannot be separated from the mixture of air as it is not present in free state. The three major components of air are nitrogen, oxygen and argon. These are separated using fractional distillation.

2. Milk of magnesia.

Explanation:

Milk of magnesia is a suspension of magnesium hydroxide in water. It has a milk-like texture. The particles are suspended in the solvent. Milk is a colloid, whereas salt solution and vinegar are solutions.

2. Fractional distillation and separating funnel

Explanation:

Miscible liquids can be separated using fractional distillation.

By this technique, components of the mixture can be separated based on the difference in boiling points. 

Separating funnel helps in separating two immiscible liquids.

In this, two layers are seen.

The denser liquid will be the bottom layer and the lighter liquid will be top layer.

On the other hand, chromatography is used in the separation of homogeneous mixtures, therefore, can not be used to separate immiscible liquid mixtures.

2. Mixture

Explanation:

Apple juice is a fruit juice made by the maceration and pressing of apples. 

so its a mixture.

4. All of these

Explanation:

A homogeneous mixture is a mixture where the components that make up the mixture are uniformly distributed throughout the mixture.

The composition of the mixture is the same throughout.

There is only one phase of matter observed in a homogeneous mixture.

• air
• sugar water
• rain water
• vodka
• vinegar
• dishwashing detergent
• steel

1. Fractional distilliation

4. Unknown-boiling-one temperature.

Explanation:

To identify the nature of a mixture, consider its sample size. If you can see more than one phase of matter or different regions in the sample, it is heterogeneous. Ifthe composition of the mixture appears uniform no matter where you sample it, the mixture is homogeneous.

2. Colloidal

Explanation:

The Tyndall effect is the scattering of light as a light beam passes through a colloid.

The individual suspension particles scatter and reflect light, making the beam visible.

The amount of scattering depends on the frequency of the light and density of the particles.

Milk is a colloid that exhibits the Tyndall effect.

2. First absorbed and then released.

Explanation:

When a mixture of iron and sulphur is heated strongly, they first absorb the energy to get excited. This is followed by the formation of a new compound iron sulphide (FeS) with the release of huge amount of energy in the form of heat and light.

3. Sugar gets mixed with water and vaporize

Explanation:

All the water gets evaporated but this is not suitable for the extraction of sugar.

Crystals as the sugar crystals gets charged by heating it in this way.

4. Chromatography

3. Fractional distillation

4. Sublimation

Explanation:

Sublimation is a method in which a solid substance directly changes to the gas phase without changing into the liquid phase. 

Ammonium chloride is separated from common salt(sodium chloride) by sublimation.

This happens because ammonium chloride is volatile in nature whereas common salt is non-volatile in nature. 

Hence when a mixture of ammonium chloride and common salt is heated, ammonium chloride changes its state from solid to vapour.

The vapours of ammonium chloride are then condensed on a cold surface.

The common salt(sodium chloride) is left behind.

3. Iodine in water.

Explanation:

Tincture of iodine is made by dissolving iodine in alcohol. It is used as medicine.

4. Iodine in alcohol.

Explanation:

Iodine dissolved in alcohol is called tincture of iodine.

2. Centrifugation.

Explanation:

Centrifugation is a process, in which suspended particles are separated from the solvent. In this process, the solution is rotated at a high rate in a centrifuge thereby separating the solute particles and the solvent.