Answer:
The balanced reaction in the acidic medium is:

Explanation:

1)
( oxidation)
Balance oxygen by adding water :

Now , balance hydrogen by adding hydrogen ions on the side where hydrogen are less.

Add electrons to balance charge where positive charge is more.
..[1]
2)
(reduction)
Balance oxygen by adding water :

Now , balance hydrogen by adding hydrogen ions by adding them on the side where hydrogen are less.
..[2]
Add electrons to balance charge where positive charge is more.
..[2]
3 × [1] + 2 × [2]
The balanced reaction in the acidic medium is:

Answer:
chemical energy into thermal energy
Explanation:
The reaction taking place is as follows
2C₂H₂ + 5O₂ = 4CO₂ + 2H₂O + Heat
In this reaction bonds present in acetylene is broken and new bond present in water and carbon dioxide are formed . In the whole process of bond breaking and bond formation , there is net loss of energy and that energy is released as heat energy .
Thus we can say that in the whole process , chemical energy is converted into heat energy .
The correct answer I believe is sunlight