# Given, the enthalpy of combustion of glucose is 3000 kJ/mol. How much of glucose one has to consume to walk a distance of 5 km, provided 150 kJ of energy is needed for muscular work to walk a distance of 1 km and only 30 % energy is available for muscular work?

(a) 75 g
(b) 150 g
(c) 30 g
(d) 180 g

Energy consumed for walking a distance of 5 km = 150 $\times$ 5 kJ = 750 kJ
1 mole of glucose, $C_6H_{12}O_6$ (180 g) gives theoretically energy = 3000 kJ
Actual energy available= $\frac{30}{100} \times 3000$ = 900 kJ
Thus for 900kJ of energy, glucose required = 180 g
$\therefore$ for 750 kJ of energy, glucose required = $\frac{180}{900} \times 750$ = 150 g