MCQ
Knocking sound occurs in engine when fuel
- AIgnites slowly
- ✓Ignites rapidly
- CContains water
- DIs mixed with machine oil
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$(i)$ $\begin{gathered}
HCN\left( {aq} \right) + {H_2}O\left( l \right) \rightleftharpoons {H_3}{O^ + }\left( {aq} \right) + C{N^ - }\left( {aq} \right) \hfill \\
{K_a} = 6.2 \times {10^{ - 10}} \hfill \\
\end{gathered} $
$(ii)$ $\begin{gathered}
C{N^ - }\left( {aq} \right) + {H_2}O\left( l \right) \rightleftharpoons HCN\left( {aq} \right) + O{H^ - }\left( {aq} \right) \hfill \\
{K_b} = 1.6 \times {10^{ - 5}} \hfill \\
\end{gathered} $
These equilibria show the following order of the relative base strength
${H_2} + \frac{1}{2}{O_2} \to \,{H_2}O + 68.3\,kcal$
$C{H_4} + 2{O_2}\, \to \,C{O_2} + 2{H_2}O + 210.8\,kcal$ Then the possible heat of methane will be.....$ kcal$
A for disproportionation reaction.
B for comproportionation reaction.
C for either intermolecular redox reaction or displacement reaction.
D for either thermal combination redox reaction or thermal decomposition redox reaction.
$MnO_4^ - + {H^ + } + B{r^ - } \longrightarrow M{n^{2 + }}\left( {aq.} \right) + B{r_2} \uparrow $