Matter is not created or destroyed: when it changes form
when it changes chemically
under any circumstances
all of the above

The law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so quantity can neither be added nor be removed.

The question was a bit confusing so I'm just going to write the answer

Explanation:

Matter can change form through physical and chemical changes, but through any of these changes matter is conserved. The same amount of matter exists before and after the change—none is created or destroyed.

the discoverers and explorers: 1. natives showed jedediah smith the way. 2. william sublette was the first cross it with a caravan. 3.joel walker and his family were the frist settlers to use it. the jumping off point: 1. founded in 1827 near where the missouri river flows into the mississippi. 2. by the 1840's, it was the most popular "jumping off" point for pioneers to stock their wagons with supplies. 3. missionaries from the church of jesus christ of latter day saints attempted to make independence their zion, or holy capital. the route west: 1. the first emigrants to oregon came by ship before the trail was established. 2. ships continued to to travel to oregon even after the overland migrations began, but they were not popular among the pioneers. 3. the fare for a sea journey to oregon was quite expensive--few pioneer families could afford it. i don't know the other three i'm sorry.

an expansion is one of two basic business cycle phases; the other is contraction. the transition from expansion to contraction is a peak, and the changeover from contraction to expansion is a trough.