pls help solve N-hmr practice problems

for practice problem 4, there is a note that says "there is a quartet at 21ppm and one at 10.5

1. For each set of spectral data below, determine the structure of the compound. Draw the structure in the space below each set of spectra. 3 points each. Compound \#2: C10H14 Compound \#3: C5H10O Compound \#4: C5H10O2 1. For each set of spectral data below, determine the structure of the compound. Draw the structure in the space below each set of spectra. 3 points each. Compound \#2: C10H14 Comnnind 42+rEH1 Comnniand HA+r2HAO