1. Should water be classified as renewable or nonrenewable? Explain your reasoning.

2. Describe the life cycle of a low mass star similar to our sun.

3. Identify the advantages and disadvantages of using coal for energy. Name at least TWO alternative sources of energy.

Renewable Resource Hydropower is renewed by the Earth's hydrologic cycle. Water has also been considered renewable, but overpumping of groundwater is depleting aquifers, and pollution threatens the use of many water resources, showing that the consequences of resource use are not always simple depletion. For low-mass stars (left hand side), after the helium has fused into carbon, the core collapses again. As the core collapses, the outer layers of the star are expelled. A planetary nebula is formed by the outer layers. The core remains as a white dwarf and eventually cools to become a black dwarf. inexpensive compared to coal ... o Two types of coal-low rank (pollutes more), and high rank.