There is one degree of unsaturation and three types of hydrogens. The δ 1.03 and 2.05 signals are in the alkane region while the signal at δ 4.37, because of its chemical shift, must have a heteroatom attached to it. The 3H triplet is produced by the 2H at δ 2.05, which hydrogens also cause the 2H triplet at δ 4.37. The hydrogens 3H and 2H produce the sextet at d 2.05. The carbon chain is CH₃CH₂CH₂-, an n-propyl group. This means that the unsaturation must be in the -NO₂ group. This does not mean that the group is -N(=O)O, a nitro group. Another possibility is a nitrite group, -ON=O, which also has one degree of unsaturation. The chemical shift chart does not include these groups, so we must find another way to distinguish between 1-nitropropane and n-propyl nitrite. Take a look at the 90 MHz spectra of the closely related ¹H NMR spectra of 1-nitrobutane and n-butyl nitrite (Scroll below the spectra at the SDBS site to see a list of the chemical shifts.). Compare the chemical shifts of the low field signals in these two spectra and you make the decision as to the structure of the unknown. See if you are correct here.