Test: Is Matter Around Us Pure - 1 - UPSC MCQ

Filtration is a method for separating an insoluble solid from a liquid. When a mixture of sand and water is filtered: the sand stays behind in the filter paper (it becomes the residue ) the water passes through the filter paper (it becomes the filtrate).

• Statement (i) is correct because a mixture is defined as being composed of more than one pure substance.
• Statement (ii) is also correct as a pure substance consists of a single type of particles.
• However, statement (iii) is incorrect because sodium chloride dissolved in water is a mixture, not a pure substance.
• Statement (iv) is incorrect because milk is a mixture of water, fat, proteins, etc., and not a pure substance. Therefore, the correct answer is Option A: (i) and (ii).

Carbon dioxide is not a mixture since it contain fixed ratio of oxygen and carbon in 2:1, which is a property of compound not a mixture.

The scattering of light by colloidal particles in a solution is known as the Tyndall effect, named after the scientist who discovered it. This effect is a result of the particles in the colloid scattering light, making the path of light visible.

A suspension is a mixture where you can see the particles floating in the liquid. They do not dissolve completely. Think of it like when you mix sand in water, and you can still see the sand particles. So, the statement is False because in a suspension, the solute particles do not dissolve but remain suspended in the liquid.

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 sulfide is a flammable, colorless gas with a characteristic odour of rotten eggs. It is commonly known as hydrosulfuric acid, sewer gas, and stink damp. People can smell it at low levels.

A solution is a homogeneous mixture because all the particles are evenly spread out, making it look the same everywhere in the mixture. Imagine mixing sugar in water until you can't see the sugar anymore. That's a homogeneous solution where everything 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 everywhere is called a homogeneous mixture. It's like when you mix something in water and it looks the same, not all lumpy or different in different parts. It's like mixing sugar in water and it looks the same no matter where you look in the glass. Cool, right?