MCQ
Borax has the molecular formula
- A$Na_2[B_4O_3(OH)_4].6H_2O$
- B$Na_2[B_4O_5(OH)_4].6H_2O$
- ✓$Na_2[B_4O_5(OH)_4].8H_2O$
- D$Na_2[B_4O_6(OH)_2].8H_2O$
Formula of borax is $Na _2\left[ B _4 O _5( OH )_4\right] \cdot 8 H _2 O$.
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$CH_3OH(l)+ \frac{3}{2} O_2 (g) $$\rightarrow CO_2 (g)+ 2H_2O(l)$
At $298\, K$ standard Gibb's energies of formation for $CH_3OH(l),H_2O(l)$ and $CO_2 (g)$ are $-166.2,-237.2$ and $-394.4\, kJ\,mol^{-1}$ respectively. If standard enthalpy of combustion of methonal is $-726 \,kJ\, mol^{-1},$ efficiency of the fuel cell will be .......... $\%$.