The burning of 1.0 g of coal produces 8.4 kcal. how many kilojoules are produced?

The conversations need to solve this problem:

1 cal = 4.184 joules
1 Kcal= 1000 calories
1 kj= 1000 joules

or a more direct approach>> 1 Kcal = 4.184 Kjoules

8.4 kcal (1000 calories/ 1 Kcal) x (4.184 joules/ 1 cal) x (1 Kj/ 1000 joules)= 35.1 Kj

or 8.4 kcal (4.184 Kj/ 1 kcal)= 35.1 Kj (same answer)