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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3nm260

Which of the following statements about the compound shown are correct? Number a spiro compound from the smaller ring, starting next to the spiro atom.

  1. AThe spiro atom is C6.
  2. BThe methyl group on the larger ring has locant 6.
  3. CThe molecular formula is .
  4. DThe correct name is 1,10-dimethylspiro[4.5]decane.

Answer: B, C

The compound is 1,6-dimethylspiro[4.5]decane. Numbering starts in the five-membered ring next to the spiro atom (C1 to C4), the spiro atom is C5, then the larger ring carries C6 to C10; the methyls take the lowest set {1,6}. The formula is C12H22 (two rings), and {1,10} is a higher set.
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