Blank 1: polar The difference in electronegativity between N and H causes electrons to preferentially orbit N, making the bond polar.
Blank 2: trigonal pyramidal There are four “things” attached to N - 3 H’s and 1 lone pair of electrons. The four things together are arranged into a tetrahedral formation. However, the lone pairs don’t actually contribute to the shape of the molecule per se; it’s only the actual atoms that do. The lone pair creates a bit of repulsion that pushes the 3 H’s down, creating a trigonal pyramidal shape (as opposed to a trigonal planar one).
Blank 3: polar The molecule as a whole is also polar because the “things” around it, though arranged in a tetrahedral pattern, are not all the same. The side of the molecule with the lone pair is slightly negative, while the side with the 3 H’s is slightly positive due to the differences in electronegativity described above.
The formula to find the density of an object is mass/volume. You know the mass in this problem is 112.8 grams, and the volume is 63 cm^3. Now you can plug this information into the density formula as 112.8/63, which is about 1.8. Now you just add the cm^3/g and you have your answer.
