Final answer:
The proton NMR spectrum of 1,1-dichloroethane is expected to show two signals due to the equivalence of the methyl and methylene protons.
Step-by-step explanation:
To determine the expected number of signals in the proton NMR spectrum for 1,1-dichloroethane, we need to consider the symmetry of the molecule and the equivalent protons. 1,1-dichloroethane (CH3CHCl2) has two types of protons: the methyl protons (CH3-) and the methylene protons (CHCl2-). Due to the molecule's symmetry, all three protons on the methyl group are equivalent and will give rise to a single signal. Similarly, the two protons on the methylene group are equivalent to each other, producing a single signal as well. Overall, we expect two signals in the 1H-NMR spectrum of 1,1-dichloroethane.