C(s) + O _ 2 (g) → CO _ 2 (g) + 400kJ C(s) + (1)/(2) O _ 2 (g) →...

$C\left(S\right) + {O}_{2}\left(g\right) \to {CO}_{2}\left(g\right) + 400kJ$

$1$ mole

$C\left(s\right) + \dfrac{1}{2}{O}_{2}\left(g\right) \to CO\left(g\right) + 100kJ . . . \left(2\right)$

$0 . 6Kg \times 1000$

$= 600gm$

Mass of $60$ pure coal

=$600 \times \dfrac{60}{100}$ (Pure Carbon)

$= 360gmNumberofmoles = \dfrac{360}{12} = 30molesofpurecarbon$

Moles of 60% pure Carbon converted into ${CO}_{2} = \left(30 - 30 \times \dfrac{60}{100}\right)$

$= 12$ mole and

Moles of 60% pure carbon converted in to $CO = 30 \times \dfrac{60}{100} = 18$ mole

Energy generated during $2$ equation $= 18 \times 100$

$= 1800kJ$

Energy generated during ${1}^{st}$ reaction.

$= 12 \times 400$

$= 4800$

Total $= 1800 + 4800 = 6600kJ$