Answer: The density of the liquid is 0.9 g/mL
. Hope this helps but I can not answer the second part. Hope that it is beneficial to you anyway! :)
(Edit) This might help you figure it out: The relative densities of an object and the liquid it is placed in determine whether that object will sink or float. An object that has a higher density than the liquid it's in will sink. An object that has a lower density than the liquid it's in will float.
Explanation:
