Which has greater precision, the 10 ml graduated cylinder or the 50 ml graduated cylinder?

The cylinder with the greater precision is the 10 ml graduated cylinder.
Precision refers to the closeness of a measurement to the true value.
A 10 ml graduated cylinder will have greater precision because it has marks for every 2 ml, this will allow you to read your measurements to two significant figures.
The 50 ml graduated cylinder on the other hand has marks for every 1 ml, this graduation will only allow the user to record measurement up to one significant figure. And you know, the more the significant figures, the more precise the measurement are.

Sugar and water are chemically combined.(a solution is chemically combined while a mixture is mixed together without bonding the molecules)