Are the following will increase or decrease the calculated density of the substance?

Question

a) part of the solid sticks out of the water.
b) An air bubble is trapped under the solid in the water.
c)Alcohol (density= 0.79 g/ml) is substituted for water (density= 1.00 g/ml) in the cylinder in measuring the volume of an irregular solid.

Answer 1

a - increase (all its volume has not been measured)
b - decrease - the measured volume will appear to be too large
c - If the object sinks, there will be no difference. If the object floats due to the lower density of the alcohol, then the measured volume will be too small, and the density too big.