The triple point of water is 273.1598 k or 0°c at 611.73 pascals of pressure. if ice is heated at pressures below the triple point, what will be the result
a) the ice melts but the water never boils
b) ice changes to a liquid and then to a gas
c) the ice passes directly into the gaseous state
d) the ice remains solid at pressures lower than the triple point

At pressures below the triple point, a solid "sublimes" ... When it's heated, it turns directly into gas, without ever being a liquid. We never see water do that, because the triple point pressure of water is so low ... less than 1% of the normal atmospheric pressure that we're used to. It's actually pretty close to the atmospheric pressure on Mars. So on Mars, ice cubes would behave like 'dry ice' acts here ... You'd see a cloud swirling around it and then disappear, as the ice turned to water vapor. But there would never be a puddle.

From negative to negative

Sorry i don’t know what to do