Answer
1. $77K$ two significant figures
2. $298K$ three significant figures
Work Step by Step
In this case, when determining the number of significant figures, we should use the Kelvin values instead of Celcius, since it will give us the value of absolute temperature. Kelvin scale is absolute, whereas Celsius is related to the boiling and freezing points of water. To convert Celcius scale into Kelvin use conversion $K= C^{\circ}+273$
$-196^{\circ}C +273=77K$
$-25^{\circ}C +273=298K$
