Which of the following is a conversion from chemical energy to thermal energy? Coal is burned to boil water. Food is digested and used to regulate body temperature. Charcoal is burned in a barbeque pit. All of the above.

All of the examples stated above involve the conversion of chemical energy to thermal energy.

Explanation:

- When coal is burnt to boil water.

Coal, an allotrope of Carbon, burns exothermically (i. e. gives off heat) to give Carbon dioxide or Carbon monoxide depending on whether the combustion is complete or not.

The chemical energy stored in Coal is basically converted to thermal energy in terms of the heat used to boil water.

- Food is digested and used to regulate body temperature.

Food, containing basically chemical substances (chemical energy), undergoes digestion process in the body and this little exothermic process too gives off thermal energy to the body.

- Charcoal is burned in a barbeque pit.

Just like the coal example, charcoal is another allotrope of Carbon which burns exothermically too, to give off heat to prepare/cook the barbecue. Simple conversion of its chemical energy to thermal energy.

All of the above

Explanation:

all of the reactions use up energy to achieve the end product.