Answer : The density of the rock is,

Explanation : Given,
Mass of the rock = 26 g
Initial volume = 13.2 ml
Increased volume = 25.3 ml
First we have to calculate the volume of the rock.
Volume of rock = Increased volume of water - Initial volume of water
Volume of rock = 25.3 ml - 13.2 ml = 12.1 ml
Now we have to calculate the density of rock.
Formula used :

Now put all the given values in this formula, we get the density of the rock.

Conversion :

Therefore, the density of the rock is,
