The temperature a liquid would boil: question incorrectly formulated or not? I have met a question in a high school physics book which I think is incorrectly formulated.
The question is this: In order to reach boiling temperature, a certain liquid requires twice the amount of energy compared to water. At what temperature does it boil?
The book says the answer is 200 Celsius.
It seems wrong to me because it does not mention the specific heat of the liquid. Knowing only the amount of heat provided is not enough to know the temperature it will reach, I think.
Am I wrong or is the book wrong?
 A: The book is wrong in the sense that it has made a lot of assumptions without actually accounting for all of them. So you are right that the question has incomplete information.
The inaccuracies in the question are as follows:


*

*In such questions, you must refer to the principle of calorimetry.
$$m_1s_1t_1=H=m_2s_2t_2$$ where $H=$heat absorbed by the body,  $m=$mass of that body,  $s=$specific heat of the body,  $t=$change in temperature of body and  the indices $1,2$ refer to the two bodies in contact

*The question does not mention the mass of the liquid, whether it is the same as that of water or anything else.

*In a similar manner, the question does not mention the specific heat of the liquid, whether it is the same as that of water or not.

*Also no mention of initial temperature of liquid.


So the question is quite vague.
A: I'd say the book is 50% wrong. For this problem, you have to assume that the specific heat is the same (or that the boiling point is the same). But either way, the problem is badly formulated. In order to solve it, you have to use the fact that this is a textbook problem and therefore must be solvable (and that's a really un-clean way of solving it). 
I guess what the book is saying is something like this: the second liquid, regardless of specific heat, takes twice the amount of energy to boil as compared to water. 
Another thing I don't like about the answer is that it is in Celsius, not Kelvin. Whenever thermodynamics is involved, Kelvin must always be used. 
A: Along with all the other reasons posted, it's flat-out absurd to think that requiring double the thermal energy would somehow change the boiling point from 100 to 200 $^\circ C$ .   Maybe from  X to 2*x Kelvins, but even then the heat of vaporization appears to have been ignored.
Edit: as thedude points out, the energy to reach boiling temperature is independent of the heat of vaporization, although the heat required to actually boil does depend on that value.
