General chemistry – Calibrating a thermometer, boiling point

These pre lap questions + the two uploaded pictures( chapter 2 + post lap questions )
1.why does one calibrate a thermometer?
2.calculate the boiling point of water if the atmospheric pressure is 630 mm Hg.
3. Calculate the density of rectangular solid, which has a mass of 25.71 g. It is 2.30 cm long 4.01 cm wild, and 1.82 cm high
4. A 10-mL pipette delivers 9.99, 10.01, 9.97, and 10.08 mL in an experiment. Calculate the mean value and the average deviation from the mean.