Is Matter Around Us Pure - 1 - Free MCQ Practice Test with solutions, UPSC

Filtration is a technique used to separate an insoluble solid from a liquid. This process involves the following steps:

• The mixture, such as sand and water, is poured through filter paper.
• The sand is trapped on the filter paper, becoming the residue.
• The water flows through the paper, known as the filtrate.

Filtration is commonly used in laboratories and industries to purify liquids by removing solid impurities.

• Statement (i) is correct because a mixture consists of more than one pure substance.
• Statement (ii) is also correct, as a pure substance is made up of a single type of particle.
• Statement (iii) is incorrect; sodium chloride in water forms a mixture, not a pure substance.
• Statement (iv) is also incorrect; milk is a mixture of water, fats, proteins, and more, rather than a pure substance.

Thus, the correct statements are (i) and (ii), making the answer Option A.

Carbon dioxide is classified as a compound, not a mixture. This is because it contains a fixed ratio of its elements: one carbon atom bonded to two oxygen atoms (2:1).

In contrast, a mixture consists of two or more substances that are physically combined but not chemically bonded. Here are some key points:

• Soap solution is a mixture of soap and water.
• Blood is a mixture of cells, plasma, and various substances.
• Coal is a mixture of different organic materials.

Each of these examples shows that the components can vary in composition, which is not the case with carbon dioxide.

The scattering of light by colloidal particles in a solution is known as the Tyndall effect. This phenomenon occurs because:

• The particles in the colloid scatter light.
• This scattering makes the path of light visible.
• It is named after the scientist who discovered it.

The Tyndall effect is commonly observed in mixtures where particles are large enough to affect light, making it an important concept in understanding colloidal solutions.

A suspension is a mixture where solute particles dissolve completely in the liquid.

A suspension is a mixture in which you can see the particles floating in the liquid. These particles do not dissolve completely. Consider the following points:

• The particles remain visible, as seen when mixing sand in water.
• In a suspension, the solute particles are suspended, not dissolved.
• Thus, the statement is False.

In a pure substance, all the constituent particles are the same in their chemical nature, indicating a uniform composition of the substance. This uniformity distinguishes pure substances from mixtures, where different components may be present.

 Let's take pure water (H₂O) as an example:

• Chemical Nature: In pure water, every molecule is made up of two hydrogen atoms bonded to one oxygen atom. This consistent chemical composition means that every water molecule has the same chemical properties.

• Example: Whether you take a drop of water from a glass or a lake, if it is pure water, each molecule will be chemically identical, consisting of H₂O molecules with no other substances mixed in.

Hydrogen sulphide (H₂S) is a flammable, colourless gas known for its distinctive smell of rotten eggs. It is also referred to as hydrosulfuric acid, sewer gas, or stink damp. People can detect its odour even at low concentrations.

The properties of hydrogen sulphide include:

• Flammable and colourless
• Characteristic odour of rotten eggs
• Commonly found in natural gas and volcanic gases

Due to its toxicity, caution is advised when handling hydrogen sulphide.

A solution is a homogeneous mixture because:

• All particles are evenly distributed.
• The mixture appears uniform throughout.
• For example, when you dissolve sugar in water, the sugar becomes invisible.

This results in a consistent appearance, where every part of the mixture looks the same.

• The Assertion is correct. A saturated solution is one where the maximum amount of solute has been dissolved at a given temperature.
• The Reason is correct. Solubility indeed determines the maximum amount of solute that can be dissolved in a solution at a specific temperature.
• However, the Reason is not the correct explanation of the Assertion. While both statements are individually true, the Reason does not directly explain why a saturated solution cannot dissolve more solute.
• Therefore, the correct option is B: If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

A mixture that looks the same throughout is called a homogeneous mixture. This means that every part of the mixture has the same composition and properties.

Key characteristics include:

• The mixture appears uniform, with no visible differences.
• Examples include salt water and sugar solutions, where the solute dissolves completely.
• It contrasts with a heterogeneous mixture, where different components are easily distinguishable.

In summary, when you mix substances and they blend perfectly, resulting in a consistent appearance, you have a homogeneous mixture.