I'd say it's A because while the energy cannot be lost, it can not be 100% efficient because if it was we wouldn't have to worry about energy.
Uh i think it is a balance combustion reaction not entirely sure tho
8
It’s 8 bc I said it was 8 ;)
(1) Francium - 0.7 Lowest
(2) Barium - 0.89
(3) Aluminium- 1.61
(4) Copper - 1.90
(5) Phosphorus - 2.19
(6) Flurorine - 3.98 Highest electronegativity in periodic lable
The third option because the elements mentioned in that selection are in the same group, they must have similar properties.
