A. Molecular solids tend to have lower melting points than Ionic so it would be Ionic if it weren't for Molecular.
Answer:
Projected area= Diameter of the bolt* thickness.
Explanation:
Between a plate and the body of a bolt, the projected area is equal to the product of the bolt _Diameter of the bolt______ and the plate ___thickness____.
Projected area= Diameter of the bolt* thickness.
Projected area is a 2-dimensional area measurement of a 3-dimensional body by projecting its surface on an arbitrary plane
Explanation:
Since, it is mentioned the there occurs no change in the temperature. This also means that there will occur no change in thermal energy of the system.
Hence, 
= 0. And, as = 0 then there will be no work involved. This means that total energy added to the house will return to the outside air as heat.
Therefore,
Q = -(19000 J + 2000 J)
= -21000 J
or, |Q| = 21000 J
Thus, we can conclude that the magnitude of the energy transfer between the house and the outside air is 21000 J.
Question 2 is because the passengers have inertia, which is a tendency to resist change in motion
