Answer:
Ar
Explanation:
does not react with anything it has a full electron shell so it does not combine and it is a noble gas
Answer:
Muscles work in pairs to move a bone.
Skeletal muscles only PULL in one direction. For this reason they always come in pairs. When one muscle in a pair contracts, to bend a joint for example, its counterpart then contracts and pulls in the opposite direction to straighten the joint out again.
Waves travel through matter, so I am 99.9% sure that is the answer.
Id look through your lesson to be sure!
