1) $\mathrm{m}_1=\frac{180}{60}=3, \mathrm{i}=1+\alpha$
Hence
$\Delta \mathrm{T}_{\mathrm{f}}=(1+\alpha) \cdot \mathrm{k}_{\mathrm{f}}=3 \times 1.86=5.58^{\circ} \mathrm{C}(\alpha<<1)$
$2)$ $\mathrm{m}_2=\frac{180}{60}=3, \mathrm{i}=0.5, \Delta \mathrm{T}_{\mathrm{f}}=\frac{3}{2} \times \mathrm{k}_{\mathrm{f}}{ }^{\prime}=7.68^{\circ} \mathrm{C}$
3) $\mathrm{m}_3=\frac{180}{122}=1.48, \mathrm{i}=0.5, \Delta \mathrm{T}_{\mathrm{f}}=\frac{1.48}{2} \times \mathrm{k}_{\mathrm{f}}^{\prime}=3.8^{\circ} \mathrm{C}$
4) $\mathrm{m}_4=\frac{180}{180}=1, \mathrm{i}=1, \Delta \mathrm{T}_{\mathrm{f}}=1 \cdot \mathrm{k}_{\mathrm{f}}^{\prime}=1.86^{\circ} \mathrm{C}$
As per NCERT, $\mathrm{k}_{\mathrm{f}}{ }^{\prime}\left(\mathrm{H}_2 \mathrm{O}\right)=1.86 \mathrm{k} \cdot \mathrm{kg} \mathrm{mol}^{-1}$
$\mathrm{k}_{\mathrm{f}}{ }^{\prime}($ Benzene $)=5.12 \mathrm{k} \cdot \mathrm{kg} \mathrm{mol}^{-1}$
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$Toluene\,\, \xrightarrow[{2.\,{H^ + }}]{{1.\,KMn{O_4}/O{H^ - }}}I\xrightarrow{{SOC{l_2}}}II\xrightarrow{{N{H_3}}}III\xrightarrow{{OB{r^ - }}}IV$ is
$2 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{O}_{2}+4 \mathrm{H}^{\oplus}+4 \mathrm{e}^{-} ; \mathrm{E}_{\mathrm{red}}^{0}=1.23 \mathrm{V}$
$(\mathrm{R}=8.314 \;\mathrm{J} \mathrm{mol}^{-1} \mathrm{K}^{-1} ; \text { Temperature }=298 \;\mathrm{K} ;$ oxygen under std. atm. pressure of $1 \;bar$)