Answer: The enthalpy change for formation of butane is -125 kJ/mol
Explanation:
The balanced chemical reaction is,
The expression for enthalpy change is,
Putting the values we get :
Thus enthalpy change for formation of butane is -125 kJ/mol
Essential amino acids
Amino acids are the molecules that make up proteins when they are linked up. There are certain essential amino acids, namely they are <span>histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
All of these must be obtained from one's diet. If they are not, the body will use existing proteins, such as muscle mass, to obtain them.</span>
The heat absorbed by the water sample for vaporization has been 6,105 kJ. Thus, option D is correct.
The heat of vaporization has been the amount of heat required to vaporize 1 gram of liquid.
The heat required for the vaporization has been given as:

<h3 /><h3>Computation for the Heat of vaporization</h3>
The heat of vaporization of water has been given as, 
The mass of water sample has been, 
Substituting the values for the heat energy absorbed, <em>Q:</em>
<em />
<em />
The heat absorbed by the water sample for vaporization has been 6,105 kJ. Thus, option D is correct.
Learn more about heat of vaporization, here:
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Answer : The correct answer for change in freezing point = 1.69 ° C
Freezing point depression :
It is defined as depression in freezing point of solvent when volatile or non volatile solute is added .
SO when any solute is added freezing point of solution is less than freezing point of pure solvent . This depression in freezing point is directly proportional to molal concentration of solute .
It can be expressed as :
ΔTf = Freezing point of pure solvent - freezing point of solution = i* kf * m
Where : ΔTf = change in freezing point (°C)
i = Von't Hoff factor
kf =molal freezing point depression constant of solvent.
m = molality of solute (m or
)
Given : kf = 1.86 
m = 0.907
)
Von't Hoff factor for non volatile solute is always = 1 .Since the sugar is non volatile solute , so i = 1
Plugging value in expression :
ΔTf = 1* 1.86
* 0.907
)
ΔTf = 1.69 ° C
Hence change in freezing point = 1.69 °C