Answer:
1. The enthalpy change for the backward reaction is –20 KJmol¯¹
2. The forward reaction is endothermic.
3. The activation energy for the forward reaction is +70 KJmol¯¹.
Explanation:
Considering the diagram given above, the following data were obtained:
1. The enthalpy change for the forward reaction being is +20 KJmol¯¹ and so, the enthalpy change for the backward reaction is –20 KJmol¯¹
2. The heat energy of the product is higher than that of the reactant. Therefore, the forward reaction is endothermic.
3. Activation energy is the minimum energy needed to be overcome in order for the reaction to proceed to product. It can be obtained from the energy profile diagram by considering the energy between the reactants and the peak.
For the question given above, Activation energy = 20 + 50
Activation energy = +70 KJmol¯¹
Answer:
Explanation:
Efficiency of the electric power plant is 
Here Temperature of hot source 
and Temperature of sink 
Hence the efficiency is
Now another formula for thermal efficiency Is

Here QI is the of heat taken from source 100 MJ ; Q2 of heat transferred to the sink (river) to be found
W is the of work done and W = QI -Q2
Hence From

Hence the of heat transferred to the river Is 
Question:
How could you use a model to show the cause-and-effect relationship between Earth's rotation and the apparent motion of the stars across the night sky?
Answer:
Gravity? or density because of the pull from the sun.
Answer:
When the moon moves between the sun for solar eclipse
When the earth moves between the sun and moon
(Extremely sorry if im wrong)
Explanation:
Answer:
A chemical bond is formed and energy is absorbed I do believe
Explanation: