<span>Exothermic reaction evolves energy due to which products get hot...</span>
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 
(ANS1)— P4 + 5O2 ---> 2P2O5
(ANS2)— C3H8 + 5O2---> 3CO2 + 4H20
(ANS3)— Ca2Si + 4Cl2 ---> 2CaCl2 + SiCl4