is this right
when a fuel is burned some of its chemical potential energy is lost as heat.
and
To convert kilojoules to joules dived the number of kilojoules by 1000 joules/1 kilojoule
Yes, although you can make heat do work so it may not be lost.
Yes, both statements are correct.
Regarding the first statement, when fuel is burned, its chemical potential energy is indeed converted into other forms of energy, such as heat and light. This process is commonly known as combustion.
As for the second statement, to convert kilojoules (kJ) to joules (J), you divide the number of kilojoules by the conversion factor 1000 J/1 kJ. This is because there are 1000 joules in 1 kilojoule. By dividing the given value in kilojoules by 1000 J/1 kJ, you can obtain the corresponding value in joules.