Partial pressure of ethanol $=4.556 \,kPa$
Total pressure $=$ Partial pressure of methanol $+$ Partial pressure of ethanol
Total pressure $=2.619+4.556=7.175\, kPa$
$X _{\text {methanol: }}$ : Mole fraction of methanol
$X _{\text {ethanol: }}$ : Mole fraction of ethanol
The partial pressure of methanol $= X _{\text {methanol }} \times$ Total pressure
$\therefore X _{\text {methanol }}=\frac{2.619}{7.175}$
$=0.365$
$\therefore$ Mole fraction of ethanol $= 1 -$ Mole fraction of methanol
$=1-0.365$
$=0.635$
Hence, the correct option is $B$.
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$(A)$ Ice floats in water.
$(B)$ Higher Lewis basicity of primary amines than tertiary amines in aqueous solutions.
$(C)$ Formic acid is more acidic than acetic acid.
$(D)$ Dimerisation of acetic acid in benzene.
${\left( {C{H_3}} \right)_2}CHN = NCH{\left( {C{H_3}} \right)_2}\left( g \right)\xrightarrow[{{{\text{N}}_2}{\text{(g) + }}{{\text{C}}_6}{{\text{H}}_{14}}{\text{(g)}}}]{{250 - 290{}\,^oC}}$
It is found to be a first order reaction. If initial pressure is $P_o$ and pressure of the mixture at time $t$ is $(P_t)$ then rate constant $K$ would be
$A\xrightarrow{{{\text{Reduction}}}}B\xrightarrow{{HN{O_2}}}{C_2}{H_5}OH$
