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(a). IF both (A) and (R) are correct and...

(a). IF both (A) and (R) are correct and (R) is the correct explanation of (A).
(b). If both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c). If (A) is correct, but (R) is incorrect.
(d). If (A) is incorrect, but (R) is correct. ltbr. (e) if both (A) and (R) are incorrect.
Q. Assertion (A): Estimation of reducing substance by the use of standard `I_(2)` is called iodometry.
Reason (R): in the reaction
`I_(2)+S_(2)O_(3)^(2-)toS_(4)O_(6)^(2-)+2I^(ɵ)`
The n factor of `S_(2)O_(3)^(2-)` is one.

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The correct Answer is:
To solve the question, we need to analyze both the assertion (A) and the reason (R) provided in the question. ### Step-by-Step Solution: 1. **Understanding Assertion (A)**: - The assertion states: "Estimation of reducing substance by the use of standard I2 is called iodometry." - Iodometry is a method used to determine the concentration of reducing agents by titrating them with a standard solution of iodine (I2). However, the assertion is misleading because it implies that iodometry is solely about estimating reducing substances, which is not entirely accurate. 2. **Evaluating Assertion (A)**: - The assertion is incorrect because iodometry involves the use of iodine to oxidize the reducing agent, not just estimating it. Thus, the assertion (A) is **false**. 3. **Understanding Reason (R)**: - The reason states: "In the reaction I2 + S2O3^(2-) → S4O6^(2-) + 2I^(-), the n factor of S2O3^(2-) is one." - To determine the n factor, we need to analyze the oxidation states of sulfur in the reaction. 4. **Evaluating Reason (R)**: - In the reaction, we have: - For S2O3^(2-): The oxidation state of sulfur is +2 (since there are three oxygens each at -2, the total contribution from oxygen is -6, and the overall charge is -2, leading to +4 from sulfur). - For S4O6^(2-): The oxidation state of sulfur is +2.5 (since there are six oxygens at -2, contributing -12, and the overall charge is -2, leading to +10 from sulfur). - The change in oxidation state for one sulfur atom is from +2 to +2.5, which is a change of +0.5. Since there are two sulfur atoms in S2O3^(2-), the total change is 1. Therefore, the n factor for S2O3^(2-) is indeed 1. - Thus, the reason (R) is **true**. 5. **Conclusion**: - Since Assertion (A) is incorrect and Reason (R) is correct, the correct answer is option (d): If (A) is incorrect, but (R) is correct. ### Summary of the Answer: - Assertion (A) is incorrect. - Reason (R) is correct. - Therefore, the answer is (d).
To solve the question, we need to analyze both the assertion (A) and the reason (R) provided in the question. ### Step-by-Step Solution: 1. **Understanding Assertion (A)**: - The assertion states: "Estimation of reducing substance by the use of standard I2 is called iodometry." - Iodometry is a method used to determine the concentration of reducing agents by titrating them with a standard solution of iodine (I2). However, the assertion is misleading because it implies that iodometry is solely about estimating reducing substances, which is not entirely accurate. ...
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