Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R)
Assertion (A) : An aqueous solution of \(KOH\) when used for volumetric analysis, its concentration should be checked before the use
Reason (R) : On aging,\(KOH\) solution absorbs atmospheric \(CO _2\)
In the light of the above statements, choose the correct answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R)
Assertion (A) : An aqueous solution of \(KOH\) when used for volumetric analysis, its concentration should be checked before the use
Reason (R) : On aging,\(KOH\) solution absorbs atmospheric \(CO _2\)
In the light of the above statements, choose the correct answer from the options given below :
- (A) is correct but (R) is not correct
- (A) is not correct but (R) is correct
- Both $( A )$ and $( R )$ are correct but $(R)$ is not the correct explanation of $( A )$
- Both $( A )$ and $( R )$ are correct and $( R )$ is the correct explanation of $( A )$
The Correct Option is D
Solution and Explanation
Step 1: Analyze Assertion (A)
In volumetric analysis, the concentration of the solutions used must be known accurately. KOH solutions are commonly used as titrants in acid-base titrations. The concentration of a KOH solution can change over time due to various factors. Therefore, it’s crucial to check and standardize its concentration before use. Assertion (A) is correct.
Step 2: Analyze Reason (R)
KOH solutions absorb atmospheric carbon dioxide (\(\text{CO}_2\)). The reaction between KOH and \(\text{CO}_2\) forms potassium carbonate (\(\text{K}_2\text{CO}_3\)) and water:
\[2\text{KOH} + \text{CO}_2 \rightarrow \text{K}_2\text{CO}_3 + \text{H}_2\text{O}.\]
This reaction consumes KOH, reducing its concentration in the solution. Hence, Reason (R) is correct.
Step 3: Analyze the Relationship between (A) and (R)
The absorption of atmospheric \(\text{CO}_2\) by KOH solution directly affects its concentration. This is the primary reason why the concentration of a KOH solution needs to be checked before use, especially if it’s an older solution. Thus, Reason (R) is the correct explanation for Assertion (A).
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Chemistry is a vast subject and for understanding its significance we can take help of following points:
- Chemistry plays an important role in understanding various subjects like physics, geology and biology.
- Chemistry is a core branch of science that explains us about the various compositional properties and interaction of matter. It also helps to understand various chemical reactions.
- Chemistry is important in order to understand the behaviour of fertilizers, alkenes, acids, salts, dyes, polymers, drugs, soaps and alloys in organic and inorganic chemistry.
- Chemistry plays an important role in various fields like healthcare, industrial, research, food, and farm activities.
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Classification of Matter
There are two ways of classifying the matter:
(A) Physical Classification:
Matter can exist in three physical states:
- Solids - have definite volume and definite shape
- Liquids - have definite volume but not definite shape.
- Gases - have neither definite volume nor definite shape.
(B) Chemical Classification:
Based upon the composition, matter can be divided into two main types:
- Pure Substances are defined as a single substance (or matter) which cannot be separated by simple physical methods. Pure substances can be further classified as (i) Elements (ii) Compounds
- Mixtures are the combination of two or more elements or compounds which are not chemically combined together and may also be present in any proportion.