NEET levelSingle correct optionDifficulty 1 of 3nm114
The total number of carbon atoms in spiro[4.5]decane is
A10
B11
C9
D8
Answer: A
Spiro[m.n] lists the atoms in each ring other than the spiro atom, smaller ring first. Total = 4 + 5 + 1 (the spiro atom) = 10, which agrees with the parent name 'decane'.