at 1 atm of pressure and a temperature of 0 degrees celsius, which phases of H2O can exist?
A.) ice only
B.) ice and water
C.) ice and water vapor
D.) water only
E.) not enough data to calculate
B, because water is changing its state from solid to liquid (it's fusion in portuguese, don't know in english), so while it's changing, water has 2 states at the same time.
