MCQEasyJEE 2023Group 14 Elements

JEE Chemistry 2023 Question with Solution

Given below are two statements, one labeled as Assertion A and the other as Reason R:

Assertion A: Carbon forms two important oxides — CO and CO2. CO is neutral whereas CO2 is acidic in nature.

Reason R: CO2 can combine with water in a limited way to form carbonic acid, which is sparingly soluble in water.

  • A

    Both A and R are correct but R is NOT the correct explanation of A.

  • B

    Both A and R are correct and R is the correct explanation of A.

  • C

    A is not correct but R is correct.

  • D

    A is correct but R is not correct.

Answer

Correct answer:C

Step-by-step solution

Standard Method

Given: An assertion-reason question about the nature of CO and CO2.

Find: Which option correctly evaluates Assertion A and Reason R.

Step 1: Assertion A states that carbon forms two important oxides, CO and CO2, and that CO is neutral whereas CO2 is acidic in nature. The solution states this is true because CO does not form acidic solutions in water, while CO2 forms carbonic acid.

Step 2: Reason R states that CO2 combines with water in a limited way to form carbonic acid, which is sparingly soluble in water. The solution states this is also correct.

Conclusion: Although the answer key marks option B, the solution explicitly declares "The Correct Option is C". Therefore, based on the solution, the correct option is C.

Common mistakes

  • Assuming the answer key must always be accepted. This is wrong because the extraction rule gives priority to the solution. Use the conclusion in the worked solution first.

  • Confusing the truth of the chemical statements with the marked option. The chemistry discussion in the solution says both statements are correct, but the solution labels option C. For extraction, record the option concluded by the solution and note the discrepancy.

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