Question

which procedure could be used to demonstrate that matter is conserved during a physical change?

This is the correct answer: Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.

give an example to me why its the correct answer.

Answer 1

Example experiment (with numbers)

Materials: electronic balance, small dry beaker (or dish) with lid, piece of ice.

Procedure and measurements
1. Weigh the empty beaker: 102.30 g.
2. Put the ice in the beaker and immediately weigh both: 152.30 g.
- Mass of ice = 152.30 − 102.30 = 50.00 g.
3. Cover the beaker (or keep it in a place where no water can spill or evaporate) and let the ice melt completely.
4. Weigh the beaker with the liquid water: 152.30 g.
- Mass of water = 152.30 − 102.30 = 50.00 g.

Result and explanation
- Before melting: ice mass = 50.00 g. After melting: water mass = 50.00 g.
- The total mass did not change even though the physical state changed from solid to liquid. This shows matter is conserved in a physical change: the same H2O molecules are still present, only their arrangement changed.
- Note: To demonstrate conservation reliably you must prevent loss of matter (no evaporation or spills) — that’s why you weigh the same closed system before and after.

This simple measured example illustrates why “weigh the ice, melt it, then weigh the water” demonstrates conservation of matter.