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Problem: Predict the number of signals you would see in the 13C NMR spectrum of 2-propanone (acetone, CH3COCH3). Step 1: Write down the chemical structure of the molecule to identify all carbon atoms. Acetone has three carbon atoms: a carbonyl carbon (C=O) in the middle and two methyl carbons (CH3) on the sides. Step 2: Use symmetry to find chemically equivalent carbon environments. The two CH3 groups are mirror images of each other and experience the exact same chemical surroundings, so they are equivalent and will merge into a single signal. Step 3: Count the total number of unique carbon environments. Environment A consists of the two equivalent methyl carbons (2 x CH3). Environment B consists of the central carbonyl carbon (C=O). Step 4: Conclude the final result. Since there are 2 unique carbon environments, the 13C NMR spectrum of 2-propanone will show exactly 2 peaks.