Which of the following substances would you predict to have the highest δhvap?

1.h2
2.f2
3.sif4
4.h2o
5.ar

Option (4) is the correct answer.

Explanation:

Heat of vaporization is defined as the heat energy which is necessarily added to a liquid substance in order to transform the quantity of the substance into a gas.

For example, in there will be presence of strong hydrogen bonding and in order to break this bond high amount of heat energy is required.

Whereas , and are all covalent compounds which are bonded together by Vander waal forces. As these forces are weak in nature hence, they require less amount of heat energy to convert into vapor state.

Hence, they have low value of . Also, Ar is a noble gas and it has only Vander waal forces. So, it will also have low value of .

Therefore, we can conclude that out of the given options have the highest .

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.