Answer:
Freezing and boiling point
Explanation:
A liquid form of any substance is an intermediate form between the solid form and the gaseous form.
Decreasing the temperature of liquid water according to the phase diagram of 
would freeze it and we would have a phase change from liquid to solid (ice) at the freezing point of water.
Similarly, heating water to its boiling point would evaporate water and we would have a phase change from liquid to gas (water vapor).
Therefore, liquid water exists between its freezing and boiling point.
Answer:
Mercury
Explanation:
While it is true that most metals are solid at room temperature, mercury is liquid at room temperature hence mercury is often designated as the 'liquid metal'.
Thus, if i find a bottle on the shelf that has no solid in it, only liquid and i know that only pure metals are stored in that area of the laboratory, then i will quickly relabel it as mercury.
Answer:
A. The cost of producing a kilowatt of power with fuel cell will be less than $30 in 2015
I would say the answer is A.
