(a) 881.1 kcal

(b) 771.4 kcal

(c) 981.1 kcal

(d) 871.2 kcal

Answer: 771.4 kcal

Given, Weight of benzoic acid = 1.89 g

Temperature of bomb calorimeter = $25^\circ C$

Mass of water (m) = 18.94 kg = 18940 g

Increse in temperature ($\Delta T$) = $0.632^\circ C$

ans Specific heat of water (s) = 0.998 cal/g/deg

We know that heat gained by water or heat liberated by benzoic acid (Q) = $ms\Delta T = 18940 \times 0.998 \times 0.632 = 11946.14 cal$

Since, 1.89 g of acid liberates 11946.14 cal of heat,

$\therefore$ heat liberated by 122 g of acid (1 mol) = $\frac{11946.14\times 122}{1.89}$ = 77126.5 cal = 771.12 kcal

(where 122 g is the molecular weight of benzoic acid)

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