The faces of a dice are marked with the numbers $2,3,5,6,7,$ and $8$. Two different positions of this dice are described. In the first position, the numbers $2,3,$ and $5$ are visible. In the second position, the numbers $2,6,$ and $7$ are visible. Select the number that will be on the face opposite to the face showing $8$.

From the two given positions of the dice, the number $2$ is common to both positions.
* In the first position, $2$ is adjacent to $3$ and $5$.
* In the second position, $2$ is adjacent to $6$ and $7$.

This means that the face with number $2$ is adjacent to four faces: $3,5,6,$ and $7$. Since a face on a standard cube can only have four adjacent faces, the remaining unmentioned number must be directly opposite to it.
The remaining number from the set $\{2,3,5,6,7,8\}$ is $8$.
Therefore, the face opposite to $8$ is $2$.