Yes, because if you assume that you have a full bucket of water and when you try to pick it up, it too heavy to pick up without a struggle so when you pour half the water out of the bucket, the bucket of water is a lot easier to pick up, thus the density of the bucket of water changes.
0 degrees and 101 kPa are the conditions that describe the standard temperature and pressure. When expressed in K, the standard temperature 0 degrees equals 273.5 K. Also the standard pressure 101 kPa equals 760 mmHg or 1 Atm.
