densities????????????????????

Question

how do you measure & compare densities of iron &magnesium

Answer 1

He, he! Dropping magnesium in water will result in its slow reaction with the water. If you're quick enough, it could work before the little bubbles of hydrogen spoil your measurement.

Try similar displacement techniques for measuring volume, but use a non-reactive liquid like vegetable oil.

Answer 2

a. weigh the pieces
b. drop them into a measuring cylinder with some water in, and see how much the level goes up. Make sure they sink.

You will then have the mass and volume, so you have the density.