Given : $T _{ f }^{\circ}=5.5^{\circ} C$

$K _{ f }=5.12^{\circ}\,C / m$

$\because \Delta T _{ f }= k _{ f } \times m$

$\Rightarrow\left( T _{ f }^{0}- T _{ f }^{\prime}\right)=5.12 \times \frac{\left(\frac{10}{58}\right)}{\left(\frac{200}{1000}\right) \,kg } \,mol$

$\Rightarrow 5.5- T _{ f }^{\prime}=\frac{5.12 \times 5 \times 10}{58}$

$\Rightarrow T _{ f }^{\prime}=1.086^{\circ} C \simeq 1^{\circ} C$