1 Copper and PVC water pipes are relatively non-toxic. 2  Copper is a natural material that has been proven to be safe to health. 3  PVC pipes are also safe. 4  Lead on the other hand is extremely toxic. 5  Lead is corrosive and can leak into the drinking water system. PVC is likewise a safe material to carry drinking water. 2  Copper and PVC water pipes do not suffer easily from corrosion, while iron corrodes relatively easily. 3  Copper is relatively easy to work with because it is much softer than iron or lead.
Advanced. Stoichiometry determines the quantitative relationships between reactants and products. Stoichiometric relationships are based on the laws of conservation of mass and energy and the law of combining weights or volumes.
Piaget emphasized the importance of schemas in cognitive development, and described how they were developed or acquired. A schema can be defined as a set of linked mental representations of the world, which we use both to understand and to respond to situations.iaget believed that cognitive development did not progress at a steady rate, but rather in leaps and bounds. Equilibrium occurs when a child's schemas can deal with most new information through assimilation.