Al examinar una mezcla de reactivos utilizando papel tornasol rojo, se obtiene una coloración azul indicativa de presencia de hidróxidos, el óxido que reaccionó con agua para cambiar la coloración del papel tornasol fue

Well, considering that the test strip when putting it in the color change solution, we consider that these test strips usually change color when the other substance is BASIC.

They usually change their color to blue

Explanation:

In the event that these test strips are contacted with an acidic solution, these strips will not change color, and will maintain their pink / fuchsia color.

space exploration has led to the development and technological improvement of many everyday items. (if this answer is wrong i will find the right answer) : )