How is the gunpowder likely different before and after being set on fire?

Which change to the system wood cause the freely-moving piston to lower?

Match each statement with the state of matter it describes

Ascientist conducted an experiment and discovered that certain plants grow faster when given a particular amount of fertilizer. anouther scientist conducted the same experiment and got similar results. which concept does this best illustrate? a) repetition b) replication c) precision d) validity