Answer :
(1) The number of grams needed of each fuel
are 19.23 g and 20.41 g respectively.
(2) The number of moles of each fuel
are 0.641 moles and 0.352 moles respectively.
(3) The balanced chemical equation for the combustion of the fuels.


(4) The number of moles of
produced by burning each fuel is 1.28 mole and 1.41 mole respectively.
The fuel that emitting least amount of
is 
Explanation :
<u>Part 1 :</u>
First we have to calculate the number of grams needed of each fuel
.
As, 52 kJ energy required amount of
= 1 g
So, 1000 kJ energy required amount of
= 
and,
As, 49 kJ energy required amount of
= 1 g
So, 1000 kJ energy required amount of
= 
<u>Part 2 :</u>
Now we have to calculate the number of moles of each fuel
.
Molar mass of
= 30 g/mole
Molar mass of
= 58 g/mole

and,

<u>Part 3 :</u>
Now we have to write down the balanced chemical equation for the combustion of the fuels.
The balanced chemical reaction for combustion of
is:

and,
The balanced chemical reaction for combustion of
is:

<u>Part 4 :</u>
Now we have to calculate the number of moles of
produced by burning each fuel to produce 1000 kJ.

From this we conclude that,
As, 1 mole of
react to produce 2 moles of 
As, 0.641 mole of
react to produce
moles of 
and,

From this we conclude that,
As, 1 mole of
react to produce 4 moles of 
As, 0.352 mole of
react to produce
moles of 
So, the fuel that emitting least amount of
is 