How is it possible for someone to put an ear to a wall and hear someone in the next room? a. sound waves can travel though solids. b. the waves travel from room to room via air. c. there must be some air in the wall so the sound can travel through it. d. sound waves change to electromagnetic waves and then back again.

The answer is A. Sound can travel through matter (solids, liquids, and gases). Sound travels faster in solids, then slower in liquids and slowest in the air. When the person in the next room makes noise, the sound travels through the air in their room, through the solid wall and in the air in your room and into your ear.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.

more words for this could be abiotic and biotic

abiotic: living organisms within an ecosystem

biotic: non-living organisms within an ecosystem