Problem: -  Falls onto the ground - The acid rain starts scouring rocks - Destroys vegetation - The lack of vegetation alters the surrounding environment.  What might be the first step of the process?

A: Acid rain is produced by chemicals that reach into the atmosphere


Problem: -  Over time, more sediment piles on top - The resulting heat and pressure transforms the organic layer into a dark and waxy substance known as kerogen - Left alone, the kerogen molecules eventually crack - The molecules break up into shorter and lighter molecules composed almost solely of carbon and hydrogen atoms - It will turn into either petroleum or natural gas -   What might be the first step of the process?

A: Dead organic material accumulates on the bottom of oceans, riverbeds or swamps, mixing with mud and sand


Problem: -  Your thermostat sends a signal to your heating system to provide heat for your home - When your oil burner is engaged, heating oil travels from the tank to the burner by way of a pump - Here the oil becomes a fine mist mixed with air - The fuel/air mixture is then injected into the burner where it is ignited in the combustion chamber - The warm air is disbursed through vents, hot water through baseboards, or by steam radiators -   What might be the first step of the process?

A: Your thermostat senses that the room temperature has fallen below your thermostat setting


Problem: -  Sound waves move parts inside the receiver - Movement causes the magnet inside to produce eletricity - Electricity is transferred through  a wire or cable - A membrane in the other persons phone is vibrated by the magnet in their telephone - Sound is produced - They hear you.  What might be the first step of the process?

A: