Statement-1 :- The temperature dependence of resistance is usually given as $R=R_0(1+\alpha \Delta t)$. The resistance of a wire changes from $100\Omega \text{ to }150\Omega$ when its temperature is increased from ${27}^{0}C$ to ${227}^{0}C$. This implies that $\alpha =2.5\times {10}^{-3}{/}^{0}C$ 

Statement-2 :- $R=R_0(1+\alpha \Delta t)$ is valid only when the change in the temperature $\Delta T$ is small and $\Delta R=\left(R-R_0\right)<<R_0$.