Final answer:
The child is unable to conserve the concept that changing the shape of an object does not alter its mass in accordance with the law of conservation of matter. This law states that there is no detectable change in the total quantity of matter present, regardless of the form it takes.
Step-by-step explanation:
If a child is presented with two identical balls of clay and one ball is molded into different shapes while the other ball remains untouched, the child is unable to conserve or understand that changing the shape of an object does not alter its mass. The law of conservation of matter asserts that when matter converts from one type to another or changes form, there is no detectable change in the total amount of matter present. This principle applies in various scenarios, whether in a laboratory or natural world.
For instance, when bread dough is baked, despite releasing an aroma and undergoing chemical changes, the mass of the loaf remains the same as the original dough. Similarly, when magnesium burns to form magnesium oxide or when tin is heated to form tin oxide in a sealed flask, there is no change in mass. The total mass of matter is conserved, according to the law of conservation of matter and the first law of thermodynamics, which also upholds the conservation of energy.