Test: Is Matter Around Us Pure (Medium) - Class 9 MCQ

Decantation involves the separation of liquid from solid and other immiscible (non-mixing) liquids, by removing the liquid layer at the top from the layer of solid or liquid below. This process can separate two liquids that do not mix, e.g., oil and water.

Distillation is useful low boiling metals like zinc and mercury. The impure metal evaporated to obtain pure metals distillate.

A homogeneous mixture appears uniform, regardless of where you sample it. Examples of homogeneous mixtures include air, saline solution, most alloys, and bitumen.

Homogeneous Mixture: Option B
Explanation:
Definition of a Homogeneous Mixture:
A homogeneous mixture is a type of mixture in which the components are uniformly distributed and cannot be distinguished visually. In other words, the mixture has a uniform composition throughout.
Distinguishing Characteristics of a Homogeneous Mixture:
- Homogeneous mixtures have a uniform appearance and consistency.
- The components of a homogeneous mixture are evenly distributed at a molecular level.
- The composition of a homogeneous mixture remains the same regardless of the sample size.
Explanation of the Options:
A:

is made up of only one kind of molecules

- This option describes a pure substance rather than a mixture. In a homogeneous mixture, multiple types of molecules are present.
B:

is one in which components cannot be distinguished

- This option correctly defines a homogeneous mixture. The components of a homogeneous mixture are indistinguishable visually.
C:

is one in which component can be distinguished

- This option describes a heterogeneous mixture, where the components can be visually distinguished. In a homogeneous mixture, the components are uniformly distributed and cannot be distinguished.
D:

is made up of different types of liquids

- This option does not accurately define a homogeneous mixture. While a homogeneous mixture can be made up of different types of liquids, it can also consist of solids, gases, or a combination of substances.
The correct answer is option B because it accurately describes a homogeneous mixture as one in which the components cannot be distinguished visually.

The sublimation process is used to separate the component from a solid-solid mixture which sublimes on heating and other components being non-volatile.

It will be a pure substance because the chemical composition is both the same(sucrose).

(i) There will be no reaction. Carbon disulphide is a colourless liquid. Iron sulphide is an ionic compound while carbon disulphide is a nonpolar molecule. Iron sulphide is not soluble in carbon disulphide, and hence the carbon disulphide remains colourless.

(ii) When HCl is added to a mixture of iron filings and sulphur powder, then iron being more reactive than hydrogen will displace hydrogen from the acid, forming its salt instead. The sulphur powder will not react with HCl. Following is the reaction between Fe and HCl

Fe + 2HCl → FeCl₂ + H₂

We need two experiments for separation of Sand, salt and Ammonium Chloride

1) Aim: To Separate Ammonium Chloride (NH₄Cl) and Common salt (NaCl) and Sand.

Materials required: Mixture of NH₄Cl and NaCl, Inverted funnel, China Dish, Cotton plug, Burner

Procedure:

i. Put the mixture in a china dish and put it on burner ii. Cover the china dish with an inverted funnel

iii. Cover the stem of the funnel with a cotton plug iv. Heat for some time v. Close the Burner when you observe vapours in the funnel

Observation: You can observe the solidified Ammonium Chloride (NH₄Cl) on the funnel's internal wall.

Conclusion-: The NH₄Cl is a volatile substance and hence got sublimed into the gaseous form on heating. When it cooled down, it got solidified on the wall of the inverted funnel.

Hence, we have separated Ammonium Chloride from the mixture, and we have a mixture of NaCl and Sand.

2.) Aim: To separate NaCl and Sand Materials required: Water, filter Paper.

Procedure:

i. Add some water to the Mixture.

ii. Use a filter paper to separate sand from the mixture through the process of filtration.

iii. Boil the remaining mixture of water and salt.

iv. Separate the mixture of water and Salt through the process of vaporization.

Carbon disulfide evaporates at room temperature, and the vapour is more than twice as heavy as air. It easily explodes in the air and also catches fire very easily. In nature, small amounts of carbon disulfide are found in gases released to the earth's surface as, for example, in volcanic eruptions or over marshes.

Because camphor directly changes to gas and sand is an insoluble substance, the only salt can be dissolved in water

In a China dish 7 g iron filings and 4 g sulphur powder are mixed. Suggest a chemical method to separate them. You can use a magnet as all the iron fillings will stick to the magnet, and hence the mixture will be separated.

Both common salt and ammonium chloride are white powdery substances and dissolve in water to form a homogeneous mixture. On filtration, none of these will separate from the liquid. A mixture of common salt and ammonium chloride can be separated by sublimation.

Electrical and Magnetic separation: Electrolytes and non-electrolytes, magnetic and non-magnetic substances can be separated by this separation technique using either electrical field or magnetic field. The magnet can be used to separate iron from sulphur.

We first analyze the question according to the information given in the question. Iodine and Aluminium Chloride Sublime; hence we cannot begin by separating them by distillation. Iodine dissolves in Carbon Tetra Chloride; hence, we can begin by dissolving the Carbon Tetra Chloride mixture to eliminate Iodine. We then filter to obtain a mixture of Aluminium Chloride and sand. Since only Aluminium chloride sublimes, we separate the mixture by sublimation.

The separation steps are thus as follows :

1) Addition of CCl₄

2) Filtration

3) Sublimation

The process of: can separate

Simple distillation is a method for separating the solvent from a solution. For example, water can be separated from the salt solution by simple distillation. This method works because water has a much lower boiling point than salt. When the solution is heated, the water evaporates.

A mixture containing iron filings and sulphur powder is spread on the white paper, and a magnet is rolled in it. The particles that cling to the magnet are the particles that cling because of iron fillings because iron gets attracted by the magnet.

The process of rusting of iron is called corrosion. Corrosion is a chemical change as the formation of iron oxide is an irreversible process.

A mixture of sulphur and carbon disulphide is an example of colloid. It does not form a uniform composition. So, the properties of the mixture are different throughout the solution. Hence, it will form a heterogeneous colloid.

Tincture of iodine is an antiseptic, also called a weak iodine solution. It is usually 27% elemental iodine, potassium iodide or sodium iodide, dissolved in a mixture of ethanol and water.

A homogeneous material or system has the same properties at every point; it is uniform without irregularities. A uniform electric field would be compatible with homogeneity.