ANSWERS: 4

Mathematically yes. Technically, probably not. From absolute zero, it's not. To find out you may have to convert metric temperatures to Kelvin and then it's only a few percentage points warmer. http://www.onlineconversion.com/temperature.htm

No, because 0 C is not the lowest it can go, 273 C is. That's absolute zero, with no molecular movement whatsoever. That's also 0 Kelvin (celsius is kelvin with 0 being the freezing point of water rather than absolute zero). That being said, 30 C is 303 kelvin, and 15 C is 288 kelvin, so is 303 twice as much as 273? No, it is not, so 30 C is not twice as hot as 15 C.

Nobody can answer this question until you explain what you mean by "twice as hot". The answer is not necessarily based on the range of possible outcomes (in fact, it is unclear what this range has to do with the answer at all). Referring to a scale that has a natural beginning (like the Kelvin scale, in which all temperatures can be only nonnegative, and the zero point corresponds to total absence of kinetic energy of molecules of any substance) has a lot more sense. For instance, if you have a certain given amount of a substance (which means that its mass does not change), then the amount of heat, that is, inner kinetic energy of molecules, of the mass at 30 degrees Kelvin is indeed twice that at 15 degrees. However, even in a relative scale like Fahrenheit or Celsius, you will need twice more heat energy to raise the temperature from 0 degrees to 30 degrees compared to raising it from 0 to 15 degrees. Would you call this "twice as hot"? I don't know, it's for you do define what you mean.

No. ... it is only +15°C hotter.
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