(1) 39. Flotation is a method to determine the __ of a particle of glass temperature refractive index density weight

## Step 1<br />Flotation is a method used to determine the density of a particle. This is based on the principle that an object will float in a fluid if its density is less than that of the fluid. <br /><br />## Step 2<br />In this case, the fluid is water and the object is a glass particle. If the glass particle floats, it means that its density is less than that of water. <br /><br />## Step 3<br />Therefore, the correct answer is "density".